A dentist, an electrician, and a carpenter decide to play a practical joke their best friend on his wedding night.

"I'll loosen some joints on his bed so it collapses when he's making love," says the carpenter.

"I'll hot wire his mattress so they'll feel immense heat while making love," says the electrician.

"Those are good ideas," says the dentist. "But my contribution's going to be a real surprise."

The next day the new husband comes to the diner to meet his friends. He says "I congratulate you guys for making the bed heat up and collapse, but I'm gonna kill whichever one of you put novocaine in the massage oil!"