Back in 1984, Jay Leno made an appearance on David Letterman's talk show. Despite their rivalry, things seemed tame enough— until Leno had the audacity to make jokes about his shady deals with NBC behind Dave's back.

As Leno's jokes went on and on, Dave calls him out by saying "I don't really need to be out here, do I?" Leno responds with a joke that rings all too true today— "I've been telling the network that for 18 months."