I perfer getting amusment this way:
Bare with me on this on:
I know my friend's work schedule at a resturant in town, so I go there and screw with the salt and pepper shakers (plastic only works with this trick), I take a penny out of my coat pocket and put it on its side vertically, then I take the salt shaker and slam it onto the penny so that it is lodged in (don't touch it at this point), then put I it in the middle of the table so when the person who busses the table moves it to the corner there will be a salt line, the person will then lift the salt shaker up to see if there is a small hole, then by that point the penny will fall out and a huge pile of salt will spread everywhere.
Needless to say, my freind got yelled at, because his boss thought he made the mess :)