Back in the ’90s, Louis C.K. was a writer for Late Night With Conan O’Brien, and like any young comedy writer would, he spent his time trying to sneak stuff past NBC’s standards and practices. Last night, C.K. returned to Late Night to reveal the story of his greatest triumph: the time he and Dino “Starburns” Stamatopoulos once got a “pearl necklace” joke on the air. Their secret? Nobody else knew what it meant. Then the segment got awkward, because it was apparent much of the audience also didn’t know what it meant, forcing Louis and Seth to dance around the subject and generally regret bringing the whole thing up. Were these people never eighth-graders?