T.J. Miller won’t do a serious drama. Ever. That’s what the 34-year-old Silicon Valley and Deadpool star emphatically vowed to Yahoo Movies during a recent discussion of his upcoming R-rated, stop-motion feature Hell & Back. (Watch exclusive red-band trailer above.)

“I’m not joking,” he told us. “I think that’s totally weird when someone becomes a great comedian — which I still have yet to do — and then they’re like, OK, I’ve spent my whole life trying to make you guys laugh and now you have to watch me cry. It’s crazy. It’s totally stupid.”

In the upcoming animated comedy Miller stays true to his self-described “blood oath” against dramatic acting. In Hell & Back, by the producers of Adult Swim’s stop-motion series Robot Chicken at ShadowMachine studio, Miller plays a not-so-svelte guy named Augie who gets pulled into Hades along with his best friend Remy (stand-up comedian Nick Swardson). The thing is, this Hell is pretty hilarious, raunchy, and boasts an all-star cast that includes Mila Kunis as a devious demon who leads the two mortals on an odyssey through Satan’s inferno. Bob Odenkirk voices the devil, and Susan Sarandon plays his angel of desire. With performances by Danny McBride, Rob Riggle, Jennifer Coolidge, Michael Peña, and more, Hell & Back’s underwold serves up a virtual who’s who of the foul-mouthed.

Miller likens the animated feature to his upcoming Marvel comic book movie in that both defy their own categories. “Deadpool is another opportunity like this. This is a movie, it’s R-rated, and it’s in a space that isn’t usually R-rated… R-rated stop motion comedy: It just doesn’t happen.”

Miller, who has done family-friendly voiceover work in the How to Train Your Dragon films and Big Hero 6 (and also a recent Mucinex ad), argues animation is tougher than live action. “I lose the most valuable asset to my comedic skill set, which is how weird looking I am,” he said. “You only have your voice. You can’t make a stupid face. In Silicon Valley a lot of my laughs come from Erlich just giving a sort of look. It really is a lot what he looks like, even my facial hair.” There’s a benefit to voicing roles, however: “You don’t have to shower before you come into work.”

While he and his Hell co-star Swardson go back to their early days in the Los Angeles comedy scene, Miller admitted he hasn’t once met Sarandon. “It’s probably good for her that they kept me away. I’m waiting for this goddamned premiere. I have to talk to her about a bunch of movies. It’s exciting.” (Fun fact: Sarandon, who has done very little onscreen singing since her Rocky Horror Picture Show Days, has a devilish ditty in the movie.)

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