Conan O'Brien Makes Background Cameo on 'How I Met Your Mother' (VIDEO)
So what was the talk show host doing on set as an extra?
Conan actually scored the walk-on gig during a 2011 charity auction in support of the Ojai Playwrights Conference. Coco mentioned the cameo on his show last summer, adding that he wanted the smallest part possible.
HIMYM co-creator Carter Bays told Vulture that O'Brien wanted to blend in.
"When we heard Conan had won the auction, we started going through all these ideas for what he could play. But then we heard back: 'He just wants to be an extra.' And we realized this was really the funniest version [of a cameo]... In New York, every now and then you'll see somebody famous at a bar, but nobody really makes a big deal out of it," he said.
Before the cameo, Neil Patrick Harris talked about Conan winning the walk on role -- and had quite an entertaining story to go along with it. Watch the clip below.