A booby trap is a device or setup that is intended to kill, harm or surprise a person, unknowingly triggered by the presence or actions of the victim. As the word trap implies, they often have some form of bait designed to lure the victim towards it. However, in other cases the device is placed on busy roads or is triggered when the victim performs some type of everyday action e.g. opening a door, picking something up or switching something on. Booby traps should not be confused with mantraps which are designed to catch a person. Lethal booby traps are often used in warfare, particularly guerrilla warfare, and traps designed to cause injury or pain are also sometimes used by criminals wanting to protect drugs or other illicit property, and by some owners of legal property who wish to protect it from theft. Booby traps which merely cause discomfort or embarrassment are a popular form of practical joke.
The Spanish word bobo translates to stupid, daft, naive, simple, fool, idiot, clown, funny man, one who is easily cheated and similar pejorative terms. The slang of bobo, bubie, translates to dunce. Variations of this word exist in other languages (such as Latin), with their meaning being "to stammer". Thus, the term "booby trap" gives rise to the idea that an individual with the misfortune to be caught in the trap does so because the individual is a "booby", or that an individual who is caught in the trap thereby becomes a "booby".
The word has also been applied to the Sula genus of sea birds, with their common name being boobies. These birds, adapted for sea flight and swimming, have large flat feet and wide wingspans, making it difficult for them to run or take flight quickly. As a result, they are considered clumsy and easy to catch when onshore. They are also known for landing aboard seagoing vessels, whereupon they have been eaten by the crew.
In approximately 1590, the word began appearing in the English language as booby, meaning "stupid person, slow bird".
Military booby traps 
A military booby trap may be used to give away the location of an enemy by triggering a signalling device, or it may be designed to kill or injure a person who activates the trap. Most, but not all, military booby traps involve explosives.
There is no clear division between a booby trap and conventional, mass-produced land mines which are usually hidden under soil, but may be triggered by a tripwire or directional mine designed specifically to work with a tripwire. Other, similar devices include spring-guns and related mechanisms such as the SM-70 directional antipersonnel mine.
What distinguishes a booby trap is that it is contrived to work in an unexpected manner that takes advantage of the victim's ignorance of the mode of operation. It naturally follows that booby trap designs must be many and varied, and for this reason the traps are often at least partially improvised from some item of ordnance, such as an artillery shell, grenade, or quantity of high explosives. However, some mines have features specifically designed for incorporation into booby traps and armies have been equipped with a variety of mass-produced triggering mechanisms intended to be incorporated into booby traps in a wide variety of ways.
A booby trap is generally concealed or disguised in some way so that it either cannot be seen or looks harmless. Typically, a booby trap will be hidden inside, behind or underneath another object.
Part of the skill in placing booby traps lies in exploiting natural human behaviors such as habit, self-preservation, curiosity or acquisitiveness. A common trick is to provide victims with a simple solution to a problem, for example, leaving only one door open in an otherwise secure building, thereby luring them straight toward the firing mechanism.
An example that exploits an instinct for self-preservation was used in the Vietnam War. Spikes known as Punji sticks were hidden in a grassy area. When fired upon, passing soldiers unknowingly take cover in the booby trapped area, throwing themselves down on the spikes.
Attractive or interesting objects are frequently used as bait in order to lure victims into triggering the booby trap. For example, troops could leave behind empty beer bottles and a sealed wooden packing case with "Scotch Whisky" marked on it before leaving an area. The rubble-filled packing case might be resting on top of an M5 or M142 firing device, connected to some blocks of TNT or to some C4 explosive stuffed into the empty fuze pocket of a mortar shell. Alternatively, the weight of the packing case might simply be holding down the arming lever of an RGD-5 grenade with a zero-delay fuze fitted and the pin removed. Either way, when the case is moved; the booby trap detonates, killing or severely injuring anyone in the immediate area. Many different types of bait object can be used e.g. soldiers will be tempted to kick an empty beverage can lying on the ground as they walk past it. However, the beer can (partially filled with sand to add weight) may be resting on top of an M5 pressure-release firing device screwed into a buried M26 grenade.
Many purpose-built booby-trap firing devices exist such as the highly versatile M142 universal firing device (identical to the British L5A1 or Australian F1A1), or Yugoslavian UMNOP-1 which allow a variety of different ways of triggering explosives e.g. via trip wire (either pulling it or releasing the tension on it), direct pressure on an object (e.g. standing on it), or pressure release (lift/shift something) etc.
Almost any item can be booby-trapped in some way. For example, booby trapping a flashlight is a classic tactic: a flashlight already contains most of the required components. First of all, the flashlight acts as bait, tempting the victim to pick it up. More importantly, it is easy to conceal a detonator, some explosives, and batteries inside the flashlight casing. A simple electrical circuit is connected to the on/off switch. When the victim attempts to turn the flashlight on to see if it works, the resulting explosion blows their hand or arm off and possibly blinds them.
The only limits to the intricacy of booby-traps are the skill and inventiveness of the people placing them. For example, the "bait object" (e.g. a cash box in a corner of the room) which lures victims into the trap may not in fact be booby-trapped at all. However, the furniture which must be pushed away in order to get to the bait has a wire attached, with an M142 firing device connected to a 155mm artillery shell on the other end of it.
A booby trap may be of any size. However, as a general rule the size of most explosive booby traps use between 250 g and 1 kg of explosive. Since most booby traps are rigged to detonate within a metre of the victim's body, this is adequate to kill or severely wound.
As a rule, booby-traps are planted in any situation where there is a strong likelihood of them being encountered and triggered by the targeted victims. Typically, they are planted in places that people are naturally attracted to or are forced to use. The list of likely placement areas includes:
- the only abandoned houses left standing in a village, which may attract enemy soldiers seeking shelter.
- a door, drawer or cupboard inside a building that someone will open without thinking of what might be connected to it. If a door is locked, this makes people believe there could something valuable behind it so they are more likely to kick it open, with fatal results.
- vehicles abandoned by the roadside, perhaps with some kind of victim "bait" left on the back seat such as a suitcase or large cardboard box.
- natural choke-points, such as the only footbridge across a river, which people must use whether they want to or not.
- important strategic installations such as airfields, railway stations and harbour facilities, all of which the invading forces will want to occupy and use.
- anything of use or value that people would naturally want to possess or which makes them curious to see what is inside it e.g. a crate of beer, a pistol, a flashlight, discarded army rucksack or even a picture torn out of a pornographic magazine.
A booby trap does not necessarily incorporate explosives in its construction. Examples include the punji sticks mentioned above and deadfall traps which employ heavy objects set up to fall on and crush whoever disturbs the trigger mechanism. However, setting non-explosive booby traps is labour-intensive and time-consuming, they are harder to conceal and they are less likely to do serious damage. In contrast, booby traps containing explosives are much more destructive: they will either kill their victims or severely wound them.
In addition to the obvious ability of booby traps to kill or injure, their presence has other effects. These include the ability to:
- demoralize soldiers as booby traps kill or maim comrades
- keep soldiers continually stressed, suspicious and unable to relax because it is difficult for them to know which areas, buildings or objects are safe
- slows down troop movement as soldiers are forced to sweep areas to see if there are more booby traps.
- make soldiers cautious instead of aggressive and confident
- create no-go areas (real or imagined) after a booby trap has killed or wounded someone
- cause a section or platoon to have to stop in order to deal with casualties, thus slowing and delaying those troops
- create confusion and disorientation as a prelude to an ambush
Booby traps are indiscriminate weapons; like anti-personnel mines they can harm civilians and other non-combatants (during and after the conflict) who are unaware of their presence. Therefore, it is vitally important for any force which places booby traps to keep an accurate record of their location so they can be cleared when the conflict is over.
Usage throughout history 
During the Vietnam War, motorcycles were rigged with explosives by the National Liberation Front and abandoned. U.S. soldiers would be tempted to ride the motorcycle and thus trigger the explosives. In addition, NLF soldiers would rig rubber band grenades and place them in huts that US soldiers would likely burn. Another popular booby trap was the "Grenade in a Can", a grenade with the safety pin removed in a container and a string attached, sometimes with the grenade's fuse mechanism modified to give a much shorter delay than the four to seven seconds typical with grenade fuses. The NLF soldiers primarily used these on doors and attached them to tripwires on jungle paths.
The CIA and Green Berets countered by booby-trapping the enemy's ammunition supplies, in an operation code-named "Project Eldest Son." The propellant in a rifle or machine-gun cartridge was replaced with high explosive. Upon being fired, the sabotaged round would destroy the gun and kill or injure the shooter. Mortar shells were similarly rigged to explode when dropped down the tube, instead of launching properly. This ammunition was then carefully re-packed to eliminate any evidence of tampering, and planted in enemy munitions dumps by covert insertion teams. A sabotaged round might also be planted in a rifle magazine or machine-gun belt and left on the body of a dead NLF soldier, in anticipation that the deceased's ammo would be picked up and used by his comrades. No more than one sabotaged round would be planted in any case, magazine, or belt of ammunition, to reduce the chances of the enemy finding it no matter how diligently they inspected their supplies. False rumors and forged documents were circulated to make it appear that the Communist Chinese were supplying the NLF with defective weapons and ammunition.
Northern Ireland 
During the "Troubles" in Northern Ireland, booby trap bombs were often used by the Provisional Irish Republican Army (IRA) to kill British Army soldiers and Royal Ulster Constabulary officers. A common method was attaching the bomb to a vehicle so that starting or driving it would detonate the explosive. According to the Sutton Index of Deaths, 180 deaths during the Troubles were the result of booby trap bombs, the vast majority of them laid by the Provisional IRA.
Middle East 
During the Al-Aqsa Intifada, some Arab-Palestinian groups made wide use of booby traps.
The largest use of booby traps (between 2000–2005, the period of the Intifada) was in the Battle of Jenin during Operation Defensive Shield where a large number (1000-2000 according to Palestinian militant captured in Jenin during the battle ) of explosive devices were planted by insurgents. Booby traps had been laid in the streets of both the camp and the town, ready to be triggered if a foot snagged a tripwire or a vehicle rolled over a mine. Some of the bombs were huge, containing as much as 250 lb (110 kg) of explosives. To counter the booby traps, anti-tank and anti-personnel mines the IDF sent armored D9 bulldozers to clear the area out of any explosive device and booby trap planted. The IDF D9 bulldozers were heavily armored and thus did not sustain any damage from the explosions, which were triggered by them as they pushed forwards. Eventually, a dozen D9 bulldozers went into action, razing the center of the refugee camp and forcing the Palestinian militants inside to surrender.
As a rule, most purpose-made military booby-trap firing devices contain some form of spring-loaded firing pin designed to strike a percussion cap connected to a detonator at one end. The detonator is inserted into an explosive charge e.g. C4 or a block of TNT. Triggering the booby-trap (e.g. by pulling on a trip-wire) releases the cocked firing pin which flips forward to strike the percussion cap, firing both it and the attached detonator. The resulting shock-wave from the detonator sets off the main explosive charge.
Simple Trou de loup booby trap: concealed pitfall with sharp spike at the bottom
Criminal and security use 
Booby traps can also be applied as defensive weapons against unwelcome guests or against non-military trespassers, and some people set up traps in their homes to keep people from entering. Laws vary: the creator of the trap may be immune from prosecution since the victim is trespassing, or the home owner may be held liable for injuries caused to the trespasser.
Computer viruses 
Many computer viruses take the form of booby traps in that they are triggered when an unsuspecting user performs an apparently ordinary action such as opening an email attachment.
Practical jokes 
Instead of being used to kill, maim and injure, booby traps can also be used for entertainment. Practical joke booby traps are typically disguised as everyday items such as cigars or packets of chewing gum, nuts or other snack items. When the victims attempts to use the item, the trap is triggered. Two of the best known examples of this are the exploding cigar and dribble glass; others include the Snake Nut Can and shocking gum. Booby traps can also be constructed out of household or workplace items and be triggered when the victim performs a common action. Examples of this include loosening the bolts in a chair so that it collapses when sat on, or placing a bucket of water on top of a partly open door so that when the door is fully opened, the bucket tips onto the victim. A variant is the water bucket which when "thrown" at the target, is full of confetti.
See also 
- Anti-handling device
- Combat engineer
- DEMIRA Deutsche Minenräumer
- Improvised explosive device
- Mercury switch
- Booby prize
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- Photos of various booby trap trigger mechanisms
- Photos of booby trap devices used in Angola
- Booby trap concepts and detection techniques
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- Photos of injuries inflicted by explosive boobytraps (Warning: graphic images)
- The M142 multi-function boobytrap firing device (technical specifications)
- Cut-away diagram and technical specifications of M5 pressure release boobytrap firing device
- Photo of M5 pressure release boobytrap firing device connected to a one pound block of TNT explosive
- Russian MC-2 antihandling device (circa 1940s) contains 200g explosives and can be used as standalone boobytrap
- Russian MC-3 antihandling device (circa 1980s) contains 200g explosives and can be used as standalone boobytrap
- Russian ML-7 antihandling device (circa 1984) contains 40g explosives and can be used as standalone boobytrap
- Russian ML-8 antihandling device (circa 1980s) contains 80g explosives and can be used as standalone boobytrap