THINGS YOU SHOULDN’T SAY PAST MIDNIGHT: A COMEDY IN THREE BEDS, Chemically Imbalanced Comedy, at the Viaduct Theater. There’s no denying the implausibility of the characters, the familiarity of the half-baked ideas, or the toothlessly risque flavor of Peter Ackerman’s lightweight sex comedy. But audiences haven’t been too put off by the sitcom echoes: the show comes to Chicago after successful runs on Broadway and beyond. Maybe because people like sitcoms. Or because these weaknesses are all strengths of screwball farce, to which Ackerman clearly aspires.

Regardless, the real problem with Things is the way it straddles genres. Ackerman has a great handle on the rat-a-tat workings of screwball dialogue as well as its endless one-upping of nonsensical stakes. But he’s assembled his mechanically sound material with a deliberateness more appropriate to what goes on between commercial breaks. The madcap momentum develops too slowly, hitting the pitch it should’ve opened with halfway through and ending when it starts getting interesting. And though Tim Smith’s direction is otherwise fine, he fails to push things along any faster.

Thanks to the charismatic cast, however, there’s a fair number of laughs. And it never hurts to have attractive actors onstage in various stages of undress. Heather A. Saliny is strong as the woman whose politically incorrect, orgasmic exclamation gets the narrative Super Ball bouncing, and as two lovers, Paul Baio and Kristen Williams make hay of the most hackneyed (but funniest) writing in the piece.