"A Merry Friggin' Christmas" is a quaint yuletide comedy about a dysfunctional family, but it's accidentally become a historic movie since it's one of the last projects Robin Williams ever filmed. Stars Joel McHale and Lauren Graham, who play a couple hitting a tough patch in their marriage, said that working with Williams gave valuable perspective into his comedy.

"I wouldn't have been surprised if he were very animated most of the time," Graham told us. "Like many comic actors I've known, actually, he was on the other side. He was thoughtful and introspective and had good ideas and was smart. But he wasn't always performing like you've seen him."

"He was just a really normal dude and super smart. He laughed a lot," McHale said. It's that thing where people say, 'Don't meet your heroes! You'll be disappointed!' It was the opposite."

We sat down with McHale and Graham to discuss Williams' intelligence, their favorite underrated Williams movies, and being two titans of speedy TV dialogue.

"A Merry Friggin' Christmas," which features costars Wendi McLendon-Covey, Tim Heidecker, Oliver Platt and Candice Bergen, is in theaters today.