Well, we certainly didn't expect Conan O'Brien to swing by The Tonight Show.
It was just announced today that the late-night host will chat it up with David Letterman on his Late Show next week.
O'Brien's appearance on May 17 will mark his fifth visit to Letterman's program and his first in 13 years.
Of course, these two will always have a unique bond: O'Brien took over Late Night in 1993 when Letterman left to do The Late Show at CBS.
But the connection doesn't end there.
When O'Brien left Late Night to host The Tonight Show in 2009, he subsequently lost the gig soon after when NBC decided to reinstate Jay Leno as host. He now hosts Conan on TBS.
Years earlier, Letterman found himself in the running to take over The Tonight Show from Johnny Carson, only to lose out to...Leno.
In addition to O'Brien, the May 17 episode will also include guests John Mayer and Regina Spektor.