Not necessarily cruel, per se, but always good for a quick laugh.
-Krazy Kitchen
=While target is away, or overnight, open up everything that doesn't activate upon opening, nor stores any frozen/cool perishables.
=Enjoy their reaction upon seeing it.
-With a door that opens outward, place a stick at the opening point of the door. Upon opening the door, stick falls on victim; potentially tripping them, or hitting them in the nuts.
-There's also the classic rubber-band on sink sprayer.
-Take victim's keys to their car, and set the radio to a station they'd never listen to, and have the volume on full (to safe enough levels) blast.
=If victim is a metalhead, switch all stations to Gospel; if Country, set to Metal; if Talk Radio, Rap.
-Replace ketchup with hot sauce (Or replace hot sauce with ketchup).
-Swap sugar and salt
-Get Valerian root (herb that smells like crap), and hide some all over a (public) bathroom, or in high traffic zones, or private zones (nobody's safe).
=Place some Valerian root on the vent grid of your victim's A/C units in their car or house. Spread the odor upon turning on the A/C.
-(WARNING: DANGEROUS) Tie a mentos underneath a soda bottlecap, and trim off the excess. Upon opening bottle, mentos falls into drink, and explodes (or soda everywhere). If the bottle doesn't become a rocket, then I advise some discretion with the detonation location (outdoors, preferably. Easier to clean up.)
-Get a box of Lego bricks, lay them across the floor of your sleeping housemate, and enjoy their eventual screams of agony as they walk over some jagged plastic bricks.
-Saran wrap the toilet, and make sure there's no glare when lights are on.
=Alternatively, get some snappers (4th of July mini-gunpowder bags), and stick them under the hardpoints of the toilet seat while the seat's down. Upon sitting on the throne, many little explosions will be heard.
=This can also be done on door hinges.
-If you can access your victim's computer, modify their monitor settings to display the desktop 180-degrees and/or mirrored.
=You can also install the
BSOD screensaver, and have a set time (Task Scheduler) for it to go off, or set the screensaver timer to something reasonable.
-If you have any creepy dolls or figurines, or a garden gnome, have them randomly move all over the place (while victim is out of view). Don't provide any explanations, and act as if nothing is off.
-Replace the contents of a wine bottle with vinegar.
=For added practicality, use apple cider vinegar, water it down plenty, and add some honey to it so it's a bottled remedy. Excellent for when you have a sore throat or an upset stomach. Works like a charm.
-Form a block of butter out of mayonnase or yogurt, if possible. Replace current stick with new one (make sure they look identical).
-Line the inside of a victim's socks or gloves with mayonnaise. You can do the same to a wash/facecloth.
These are just some classics we did as kids and during April Fool's Day. We got mean. I need to recall some more pranks we did.