The nastiest practical joke I've ever heard of involved taking cans of Great Stuff foam sealant and freezing the cans in liquid nitrogen. Then the cans are cut off with tinsnips and welder's gloves, and the slugs of frozen foam pulled out, and stuffed under the dash in a car. Roll up the windows, lock the doors and wait for it to thaw out.
Liquid nitrogen makes for some "cool" fun. A friend wanted to return some Tupperware. He was told they'd accept the stuff only if it was defective.
He dipped the stuff in liquid nitrogen and shattered all of it by dropping them on the floor. He returned the pieces in a bag and got his money back after he told them the stuff broke. He didn't tell them about the liquid nitrogen.
That's nasty.
One I heard of back in mt misspent youth: on a warm, sunny day, completely cover your victim's front windshield with liquid dish detergent, then generously apply a good layer of oatmeal on top of that. The sun bakes it on the windshield, and it's supposed to be a pain to clean off (but the soap provides lots of fun bubbles).
I don't know if it really works, and I'm too old and respectable (hah!) now to try it.