In the 1990s, Louis C.K. was writing for Late Night With Conan O'Brien, and last night he returned to the show, now helmed by Seth Meyers. While working on the show in the '90s, C.K. was nominated for an Emmy for his work... but probably not for this one joke.
Last night he told Meyers about a "pearl necklace" joke (let us Google that for you prudes out there) that he slipped in during the intro via the announcer one night, but that otherwise wouldn't have cleared NBC's standards and practices.
It wasn't really THAT bad.