Woodward and Bernstein's exposé All the President's Men reports that many staffers who had attended the University of Southern California such as Donald Segretti, Tim Elbourne, Ronald Louis Ziegler, H. R. Haldeman and Dwight Chapin had participated in the highly-competitive student elections there. UPI reporter Karlyn Barker sent Woodward and Bernstein a memo "Notes On the USC Crowd" that outlined the connection. Fraternities, sororities and underground fraternal coordinating organizations such as Theta Nu Epsilon and their splintered rival "Trojans for Representative Government" engaged in creative tricks and underhanded tactics to win student elections. Officially, control over minor funding and decision-making on campus life was at stake but the positions also gave bragging rights and prestige. It was either promoted by or garnered the interest of major political figures on the USC board of trustees such as Dean Rusk and John A. McCone. It was here that the term ratfucking had its origin. It is unclear whether it was derived from the military term for stealing the better part of military rations and tossing the less appetizing portions away or if the military adopted the phrase from the political lexicon.
The term was made famous in Australia after the phrase was attributed to then Prime Minister Kevin Rudd at the 2009 Copenhagen Climate Change Summit. During the 2016 Republican Party presidential primaries, candidate Ted Cruz said "Trump may be a rat, but I have no desire to copulate with him", a reference to the term. 
Usage in the U.S. military
The term ratfucking (rat in this case is shorthand for ration) is the unofficial slang term used by soldiers in the U.S. Army to mean the targeted pillaging of MREs (Meals Ready-To-Eat), which the U.S. military calls field stripping. It refers to the process of opening a case of MREs, of which there are twelve in a box, then opening up individual MRE packages, and removing the desired items (generally M&M's and other sweets), and leaving the unenticing remainder.
A more benign use of the term "ratfucking" was commonplace in Southern California (and possibly other) college slang in the late 1950s to at least the early 1960s, meaning a prank. Around that time, Tony Auth was the cartoonist for the UCLA Daily Bruin. One of his cartoons showed a large, inebriated rat suggesting to another rat, "Let's go PF-ing tonight!", a play on ratfucking or "RF-ing". The lead story in the January 6, 1961, California Tech, Caltech's student newspaper, was headlined, "Tech Scores First Televised RF". The article chronicled the Great Rose Bowl Hoax, which had just taken place. A political context was irrelevant to such usage; at the end of the article, an Editor's Note both explained and bowdlerized: "RF (for Royal Flush) is a contemporary college colloquialism for a clever prank."
- Matt Taibbi, Meet Mr. Republican: Jack Abramoff, Rolling Stone, March 24, 2006.
- "University of Southern California Trustees (1979)". www.namebase.org. Retrieved 2016-05-09.
- "From CIA to USC: Biography of a Trustee". www.namebase.org. Retrieved 2016-05-09.
- "Rats from a sinking summit - Fully (sic)". Fully (sic). 2010-06-09. Retrieved 2016-05-09.
- "Ted Cruz Blames Donald Trump for 'Garbage' National Enquirer Story".
- Wright, Evan (2005). Generation Kill. Penguin. p. 61. Retrieved 2016-08-03.
The process of tearing through an MRE and picking out the goodies is called "ratfucking". Colbert's team maintains a ratfuck bag in their Humvee for all the discarded MRE entrées, saving them for a rainy day.
- Edmund Wilson, The Twenties, ed Leon Edel, Farrar Straus and Giroux, 1975, p. 116