It should be noted by people wishing to play practical jokes,

It should be noted by people wishing to play practical jokes, that
some people take them dead seriously. Such people tend to escalate
the level of jokes by a couple of magnitudes. My three favorite stories
are from different colleges.

One joker sprinkled finely ground powdered milk underneath his
victim's sheets. It acts like powdered sugar in the sense that, as you
sweat in your sleep, it dissolves and comes up through the sheets onto
your body and into your pores. But your sweat makes it sour, and when it
gets into your pores, it stays there. You smell very strongly of sour
milk for about a week (4 days if you shower and sauna every day). The
next weekend, when the joker was walking back from a party, three guys
jumped him. They were dressed in ski masks and painter's suits (those
light paper/cloth jumpsuits that people wear to paint autobodies). They
stripped, tied, blindfolded and gagged the joker, and spraypainted
him blue. No one was ever caught.

In another case, a yuppy practical joker taped a guy's car closed with
strapping and duct tape (the thing apparently looked like a ball of tape
when he got through). For those of you that don't know, the adhesive on
such tapes ruins a car's paint job, and can, if you try to remove it en masse,
even take off chips of paint and door guards (especially in winter). Two days
later, the yuppie's BMW was found with all four of its racing radials slashed
to ribbons. The yuppy of course, called the police on the guy who's car he
taped. The guy did not admit to slashing the tires, as opposed to the yuppie,
who told the police why he thought the other guy was responsible (ie: he
admitted to the police that he taped the other car). Charges were never
pressed about the BMW (lack of evidence), and charges were pressed about the
car taping. Did the guy actually slash the BMW wheels? He always claimed
that he didn't (of course the last time I knew, the statute of limitations
wasn't up yet).

Then of course there's the people who take the direct route to revenge.
Some guy thought he would make a very large, easy going, farm boy feel more
at home. So he got some fresh pig manure and dumped it in the farm boy's room.
The very large farm boy, apparently lacking a cultured sense of humor,
beat the living shit out of the joker. Then he told the joker that if it
happened again, the joker would eat the pigshit. Nobody doubted him.

So be very careful who you decide to pull a practical joke on, because they
may not think it's as funny as you do.