Muriel's date thinks he has unzipped her leather pants when he has actually just unzipped the beanbag.
Mood Whiplash follows immediately afterward. Muriel collapses in choking giggles which Rhonda's dates mistake as some kind of distress. Naked, one man tackles Muriel's date to the ground while the other, also naked, tries to identify what is wrong with her. Her attempts to control her choking giggles are not helped by the cock bouncing around right in front of her face.