I once put a rubber band around the trigger for the spray nozzle on the kitchen sink and aimed it towards where a person would stand. Sure enough, my wife eventually went to turn on the faucet and got a nice blast of water onto herself, and the floor. She quickly turned the faucet off and came and beat me up for a moment, and then went back and grabbed a sponge to clean up the floor. She then turned the faucet back on to rinse the sponge, and got blasted again.
I was laughing so hard.