A churchkey initially referred to a simple hand-operated device for prying the cap (called a "crown cork") off a glass bottle; this kind of closure was invented in 1898, although there is no evidence that the opener was called a "church key" at that time. The shape and design of some of these openers did resemble a large simple key.
In 1935, beer cans with flat tops were marketed, and a device to puncture the lids was needed. The same term, "church key", came to be used for this new invention: made from a single piece of pressed metal, with a pointed end used for piercing cans — devised by D.F. Sampson for the American Can Company, who depicted operating instructions on the cans, and typically gave away free "quick and easy" openers with their beer cans.