Conan O'Brien and David Letterman Conan O'Brien and David Letterman

Conan O'Brien stopped by the Late Show with David Letterman Thursday and — surprise! — they had quite a lot to catch up on since O'Brien last visited in 1999.

However, the two late night hosts didn't wait long before getting to the good stuff — aka bashing their shared enemy, Tonight Show host Jay Leno. "You know Jay is watching right now," O'Brien says. "He's getting a live feed in a satellite truck right now. He's watching every second."

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In the interview, Letterman tells O'Brien he considers the period when O'Brien was fired from The Tonight Show gig "the Golden Age of broadcasting." Letterman also admits he was "delighted" by the turn of events, which saw O'Brien unceremoniously ousted from the gig after just nine months and replaced by his predecessor, Leno.

"I will tell you, and this is honest, the only consolation I took during that period was that you were happy," O'Brien responds. "If this is bringing you some measure of joy, then to hell with my career."

Watch the clip below:

O'Brien's full sit-down with Letterman airs Thursday at 11:35/10:35c on CBS.