Church key

The term in the beverage-opening sense is apparently not an old one; Merriam-Webster finds written attestation only since the 1950s. Several etymological themes exist. The main one is that the ends of some bottle openers resemble the heads of large keys such as have traditionally been used to lock and unlock church doors. It’s also more than probable that an irreverent joke was attached as well, in that drinking beer was an unchurchly thing to do.

A church key initially referred to a simple hand-operated device for prying the cap off a glass bottle. Called a "crown cork" and later a “bottle cap”, this kind of closure was invented in 1892, with a patent awarded to William Painter. Two years later, Painter also received a patent on an opener, then called a "bottle cap lifter", to be used with the caps.

While 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 and licensed by the American Can Company, which depicted operating instructions on the cans, and typically gave away free "quick and easy" openers with cases of their canned beer.