a classic...

...and still in use to this day - and always very tempting to buy the can to wrangle the key!


On October 2nd 1866 ' J. Osterhoudt patented the tin can with a key opener (“Method of Opening Tin Cans,” U.S. Patent No. 58,554). 
An ancestor of the “pop top” and “pull tab,” the “key” was used to roll a thin top from a can.'

The can opener has had many incarnations since the hammer and sharp pointy tool required to open the first cans of preserved foods in 1813.
The lever openers  ( many a student has opened a can of beans and even more usefully a bottle of beer with  one of these), rotating wheel openers ( hopeless!), the electric version of the latter  and the delightfully named FRED.
'...device that incorporates a small spoon at one end and a bottle opener at the other is currently employed by the Australian Defence Force and New Zealand Army in its ration kits. The  Field Ration Eating device  is known by the acronym "FRED". It is also known as the "F***ing Ridiculous Eating Device".