The girlfriend, unfortunately, is Uma Thurman, who didn't have a good work year last year (except for her brief stint in The Producers, where she was one of the few saving graces in that disaster). She's gone from being Quentin Tarantino's muse to playing "the girl" in a number of clumsy, Manhattan-based sex-comedies, first with Prime and now in this B-picture in which she plays Jenny Johnson, the mousy, bespectacled woman who has a super secret — if only she'd kept it to herself.

Though Jenny seems excessively neurotic (there are all those dashes to the toilet), Matt allows himself to be seduced by her. Before long, she's breaking his bed — literally. But then she would, because she's "super." She is, in fact, G-Girl, the heroine of Gotham.

Befitting a superhero, G-Girl has an archenemy, Professor Bedlam (a wasted Eddie Izzard), who was once her closest chum in high school. We learn via flashback that a crashing meteor hampered the soon-to-be mortal enemies' first attempt at backseat fumbling. The two go to investigate the crash site, where they have a fateful encounter with the meteor: Jenny gains super powers, while Professor Bedlam, or Barry, as he was known in his youth, dedicates his life to evil.

When Matt finally breaks up with Jenny, she goes berserk and vows to seek vengeance against Matt and against the woman whom Jenny thinks Matt loves, his office colleague Hannah (Anna Faris).

It's Bedlam who will be on hand to ask Matt if he will join him in helping neutralize Jenny with her own version of kryptonite.

And so it goes. This could have been an interesting satire of the superhero condition, a live-action The Incredibles, perhaps. There are a few attempts to send up aspects of Superman (the Manhattan fly-over with the two lovers clutching), though nothing is ever really that winking or knowing. Director Reitman, like far too many directors of his generation, doesn't even seem to possess much in the way of basic film knowledge, as he passes up a great opportunity to burlesque Hitchcock's Saboteur — a film Reitman probably hasn't even heard of.

Instead, My Super Ex-Girlfriend is another steaming pat of jokes for the lowest common denominator, scripted with some of the dimmest witticisms imaginable passing as dialogue. After destroying Matt's bed during their coital exertions, Jenny says, "I'll buy you a new one." MATT: "A bed or a penis?" JENNY: "Both." And this is one of the script's cleverest exchanges.