My brother told me that he pulled this when he was a young, foolish physics student.
There was a certain restaurant that the students sometimes ate at, when they could afford no better - a real greasy spoon. The food was terrible and the service was worse.
One day, after a particularly revolting meal, my brother decided on revenge of sorts. He got a flask full of liquid nitrogen, and took it to the restaurant; he ordered a hamburger, took it back to his booth, and soaked it in the liquid nitrogen until it froze solid. Then, he took it to the front cash, complaining loudly that there was something wrong with his hamburger - and, to the amazement of the staff, shattered it. 
[Disclaimer: I didn’t actually witness this]
One thing I did witness wasn’t a deliberate practical joke … again, it involved my brother and liquid nitrogen.
One of the wierder effects of liquid nitrogen is that, if you throw it on the floor, it scoots along like a puck on an air-hockey table (like a boiling drop of water on a hot stove). For some reason, when it does this it tends to pick up the dust on the floor … thus, it looks much like a hissing, steaming, boiling and hairy ameoba shooting rapidly across the floor.
My brother was demonstrating this to kid brother (me) when we believed we were alone in the physics building one night - he tossed a bucket full of the stuff on the floor in a hall outside a lab he was working in, and we watched as it scooted down the corridor - and then it bounced off a wall and scooted down another corridor and out of sight - and we heard a horrid scream.
We ran down to that corridor and looked - to see a janitor running for his life, with “the blob” after him … it evaporated completely before he reached the next door, so when he turned around, it was gone.
The cruel part was, we were so afraid of getting in trouble, we didn’t tell him what happened - we pretended to know nothing about it. So the poor chap never learned exactly what was chasing him in the Physics building late one night.