The bunch of manufacturing TECHs, at Qantel, Hayward, Ca were wild (and smart).
There was always the 'Boots under the door, to the toilet: obvious someone in there ?' No.
Stupid stupid stupid.
The clean room guyes made hard resin 'spills', that's a paper cup looking like it got knocked over by accident and looks like a mess of liquid spilled out.
Sounds stupid, but I guess stupid has its own particular strength. Worked to make the new guy start dividing with his belt, and kept checking his calculator.
I don't know what those cruel bast's thought, that that could even be funny!
Oh and now realizing, you didn't specify 'Practical Jokes...
I know you can get freon to explode a shrink tube.
Place tie wraps on ends and fill w freon. (Place 'bomb' in aisle). Eventually, room temperature acts to raise freon pressure, and ... BAM