When I was delivering auto parts 20-odd years ago, mechanics used to have their new apprentices call our shop and order a "can of compression". We went so far as to keep a handful of new, unopened empty cans complete with labels on them that we'd send out. Of course when the newbie apprentice opened the can there was nothing in it. The mechanic would then chastise them for letting the compression get out. LOL

Another funny trick one of the shops pulled on a new driver we had was to hook the left-turn signal light wire up to the horn in her truck.