Conan O'Brien will be on an episode of How I Met Your Mother next season, though tragically not as the mother, which would be the best twist the show could possibly pull off. Instead, O'Brien will appear as an extra in an upcoming episode because he won a charity auction for a walk-on role. "The producers were saying, 'We'll write you in as a character.' But I think it's much funnier if I'm just in the bar, in the background," O'Brien joked. The story starts at 4:44 and it is charming.
O'Brien actually secretly appears on every episode of How I Met Your Mother: There's a moment in the opening credits when Neil Patrick Harris looks just like Conan making a crazy face. It's true!