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.

It was a 30 Rock homecoming for David Letterman on February 10, as the former Late Night with David Letterman Host unexpectedly popped up during Jimmy Fallon's Tonight Show monologue. The hilarious moment came alongside Paul Shaffer and the World's Most Dangerous Band's own return to NBC,

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.