Howard Stern will be a guest on "Late Show with David Letterman" June 8

It's likely that David Letterman's ratings will get a bump this coming Monday, the beginning of his second week facing off against "The Tonight Show with Conan O'Brien." A source tells us that Howard Stern will be a guest on the program that night. "Howard Stern hasn't done a late night show since 2007," says the source. "Letterman's booker asks for him all the time but he almost always declines. Monday's booking is clearly a favor to an old friend in an attempt to give Letterman a ratings surge as Conan's 'newness' wears off and his guests aren't as top notch. However, Howard did say that this is in no way a 'Fuck You' to Conan. He likes Conan and wishes him well.... especially because Howard hates Leno. Howard has said that he will once again do The Tonight Show since it is no longer hosted by a 'Shithead.'"

In the past, Stern has accused Leno of stealing one of his bits to create "Jaywalking." (Leno also lured away former Stern player "Stuttering John" Melendez, who became just plain John Melendez when he took over announcing duties on Leno's "Tonight.")

Conan's guests on Monday will be David Duchovny and Anna Friel.