David Letterman pranks Richard Simmons
When Richard Simmons appeared on Late Night in 2006, it seemed as though Letterman was deeply irritated by the eccentric fitness instructor, especially when Simmons wouldn't stop trying to promote a food steamer. The interview was quite uncomfortable until Letterman decided to pull a little prank on Simmons.
Simmons tried to demonstrate how the steamer operated, but when he hit the power button, smoke began to billow out of the machine. Seconds later, it burst into flames. Simmons screamed and leaped from his chair. Letterman, on the other hand, sat there and laughed, since the whole thing was a prank he had orchestrated.