According to Café Flesh, after a nuclear apocalypse, most of the world's surviving humans are "Sex Negatives," who become physically ill when they try to engage in sex acts. Those who are "Positives" are forced to take part in Café Flesh, a theater in which they have sex for the entertainment of the Negatives. But when a very special, very sexy Positive shows up, one Negative girl begins questioning just how sick sex really makes her, causing a rift between her and her boyfriend (all of which certainly sounds like something Rob Zombie would draw).
The scene in question starts with Max Melodramatic, the cabaret's MC, doing a series of impressions, which leads to a performance that suggests banging more than displays it. There are striped corsets, snapping disembodied hands, and a weird sliding platform that functions as a sort of sex swing. The moaning from More Human kicks in at about the 41-minute mark, as the performance reaches its peak (as it were).
Watch the scene from Café Flesh that opens up More Human Than Human below: