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.

TV legend David Letterman made a surprise appearance on NBC’s “Tonight Show” on Monday night during host Jimmy Fallon’s opening monologue. It was Letterman’s first appearance on the show since 1992, when Johnny Carson was host.

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.

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,

David Letterman made a surprise cameo on The Tonight Show Starring Jimmy Fallon on Feb. 10, interrupting Fallon's monologue to welcome his longtime musical director Paul Shaffer and The World's Most Dangerous Band,

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. “Is this the 23rd hour of the Today show?” Letterman asked.