Dave and Billy teamed up for this Funny or Die video.

It's still hard to believe, but David Letterman will be taping his last episode of The Late Show on May 20th. After that, no one is sure what his plans are, even him. So to get some suggestions, he walked the streets with Billy on the Street's Billy Eichner to ask random passersby in this special segment for Funny or Die. They got a few good ideas, and a lot of confused stares. You can't blame these people for being bewildered, though. How often do you encounter two comedy legends on the street?

Sources: Funny or Die