How I Met Your Mother - Chris Elliott, Cobie Smulders, Josh Radnor, Neil Patrick Harris How I Met Your Mother - Chris Elliott, Cobie Smulders, Josh Radnor, Neil Patrick Harris

Richard Heene is not exactly the first name that comes to mind when thinking of model dads, but the father of Balloon Boy was exactly who Chris Elliott looked to when he joined How I Met Your Mother as Lily's estranged father.

"When I was shooting it, the whole Bubble Boy thing was going on, so I was imagining that father. I think if that's what he was into, he would've sent her off in a balloon!" Elliott tells "That's the kind of dad he was when she was growing up — a guy obsessed with invention."

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Lily's pop, Mickey, isn't obsessed with helium balloons or any storm-chasing device, but rather creating the next hip board game. Among his hopeful creations are Car Battery and Diseases!, his latest masterpiece which he unveils on Monday's episode. "He's sort of been obsessed with that his whole life and probably did not have the best relationship with Lily growing up because of that," Elliott says.That rough childhood resulted in an estrangement three years ago and no invite for dear old dad to walk Lily down the aisle at her wedding to Marshall ("She probably didn't want him to bring any games.") But since Thanksgiving is about forgiveness and all, Marshall seeks to make amends between father and daughter, inviting Mickey over for dinner."She slams the door in my face, but I weasel my way in," Elliott says. "He does love Lily. He still brings the game over, but he realizes his mistakes. He realizes that it's time to make up for lost time."

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Elliott, who, like

Mother creators Carter Bays and Craig Thomas, is a Late Show David Letterman alum, says he has been a fan of the show ever since he saw the "Showdown" episode — in which Barney thinks Bob Barker is his father — on a plane. "I was laughing out loud and I thought it was the funniest I'd ever seen.""Carter and Craig have been able to take that late-night-comedy humor and inject it into sitcom characters that you believe. I get to be in these surreal flashbacks that are really fun for me to do, but at the same time, I also have to act and be the believable dad in a couple of moments, so it's fun to go back and forth," he says. "My show, Get a Life, was, like, all surreal and you never believed the relationships. But on Mother, you believe, but they can also go wherever they want with these flashbacks, which I think is brilliant. I love the concept of this show."And the cast? "Horrible," he deadpans. "No, the cast is really fantastic. They're also incredibly nice people. They're all people you want to hang out with in character and out of character."In character, Mickey certainly seems to have won over the gang. The episode, titled "Slapsgiving 2: Revenge of the Slap," will, of course, feature Marshall's fourth Slap Bet with Barney. "I have a hand-slapping at the end," Elliott teases.

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The comedian, whose last extended TV guest stint was as Peter MacDougall on Everybody Loves Raymond, is only signed on for one episode, but says he's "always available" to return. "They're all so great and so in sync with each other. For that reason alone, I want to go back," he says.In the meantime, he'll play the role of proud papa, watching his daughter, Abby Elliott, on Saturday Night Live, on which he worked during the 1994-95 season. The Elliotts are the first parent-child duo to be SNL cast members. So will dad ever drop by?"I don't think anyone who watches SNL has any idea who I am anymore!" he laughs. "Maybe after [the Mother episode] airs, they'll know. ... I think the only way I'll end up on SNL is if Abby gets sick and can't do the show, so they call me. It'll be like Mommie Dearest, which no one wants to see!"