In their show “We Used To Go Out” about relationships and the demises of those relationships, Jason Mantzoukas and Jessica St. Clair break a lot of new ground and show a lot of originality in playing out transgressive scenes as themselves and other characters. The duo have a rapport from working together in “Mother,” a UCB improv group regularly featured on Saturday nights.

The subjects are raw -- oral sex, masturbation, threesomes -- but all of them are made funny because Mantzoukas and St. Clair play out a series of self-delusions in their characters about what they do that make the humor more than just laughing at vulgar sex jokes, and rooting it in recognizable situations.

In the show’s sketches, Mantzoukas steps out of himself a more than Jessica does, at points also taking on roles as a flighty girlfriend of Jessica’s and as “Scooter,” an obnoxious guy Jessica goes out with after breaking off her long-term relationship with Mantzoukas himself. His other characters are distinct enough that they’re easy to grasp.

The closing sketch is especially well executed, nimbly handling surprises achieved by both breaking the fourth wall and successfully incorporating a well-known recent movie as shorthand for just how pathetic and despairing Mantzoukas (playing the version of himself) gets.

The biggest laughs of this show are well set up by the characterizations by Mantzoukas and St. Clair. The punchlines typically mean something more than just dirty jokes.