You’ll be surprised to discover that it’s actually smartly written and expertly pulled off.

The movie's reason for being is the chemistry between Gleeson — mop-headed and awkward, an idealistic milquetoast wearing a pajama top as a shirt — and Church, mustachioed and oozing testosterone, but coolly incisive despite the dumb misogyny of Grady's lines.

Yes, it’s an R-rated “How I Met Your Mother,” without the mother. But the Jeremy Catalino banter sparkles, with Gleeson gifted with assorted tirades, manifestos and shrieking lectures (to frat boys and the compliant “little sisters” who show up for their beer busts).

A plucky ensemble fails to elevate Crash Pad, a forced, formulaic revenge comedy about an obnoxious slacker whose new housemate turns out to be the husband of his older ex-mistress.

The movie’s premise isn’t as bad as the forced, unnatural dialogue. Even the reliable Ms. Applegate and Mr. Church can’t salvage the screenwriter Jeremy Catalino’s clumsy lines.