This one’s more in the field of practical jokery than true nastiness. But as an oldline advocate for that form of fun, I’ll vouch for Jerald Jordan’s idea for the doors in you office factory. Buy a long non-tapered punch at the hardware section of a department store or regular hardware shop. Arrive early at your office and use the punch and a small hammer to remove the pins that hold the two or three hinges to the inner office doors.
“The point is that the doors will open and close a couple times, then fall loudly to the floor. Hide somewhere and watch the action. People panic, scream, faint, and have seizures. It’s mammoth fun.”