I heard this at the hospital, it was something that they dealt with recently. It is an example of how just a bit too much stupidity/lack of imagination can lead to catastrophe.

A group of men were having a bachelor party. A lot of drinking. Eventually towards the end of the night, the groom falls into a drunken sleep. His best man - also drunk - decides this is a great time to do a prank on him.

He puts rain boots/wellington boots on the sleeping groom and fills the boots with window sealant. I'm sure he imagined the groom waking up with some boots on, seeing that he can't remove them, and everyone having a laugh about it.

What the best man didn't anticipate was that the sealant expanded and hardened, cutting off the blood supply to the lower legs and causing a lot of pain. The groom woke up in agony and was taken to the hospital.

The groom's lower legs had to be removed and the best man hanged himself a couple of days later.