If ya wanna have a little fun and make a couple guys jump get your self those little door alarms with the 100+ dB piercing noise. The kind where you attach a small magnet to the door jamb and align the other piece to the door. When you seperate the two the screeching starts.

We have alot of fun around the office and shop with these. Attached to lap drawers on peoples desks. Their chairs. The fridge door. Tool boxes.

We also use alot of those "door poppers" which are like little lady fingers with a string coming out of each side and when you pull the strings the thing explodes. It makes it alot easier to fix them to things with little string extensions tied on. These work real well on folding chairs.