John Oliver wasn't the only late night icon to crash this week. "The Tonight Show" started Monday off with a surprise appearance from the now-retired David Letterman, who poked fun at Jimmy Fallon while reuniting with bandleader Paul Shaffer.

On Feb. 10, David Letterman stopped by “The Tonight Show Starring Jimmy Fallon” while his former bandleader, Paul Shaffer, and his World’s Most Dangerous Band filled in for the Roots. It marked Letterman’s first “Tonight Show” appearance since Johnny Carson was host, back when the program still taped in Los Angeles.

David Letterman - with help from some flour tortillas - made a return to the late-night stage Monday. Letterman crashed Jimmy Fallon's Tonight Show monologue Monday night, wandering onto the stage as Fallon was making some jokes about Sunday's Super Bowl.