Another friend mentioned a man she’d been dating, whose erotic repertoire included withdrawing his member at key moments to thump it on her. After puzzling over it with friends, she finally figured out: It’s a porn move. Listen, if you’re a professional showing off his stuff for the camera, that sort of thing almost makes sense. Out of context, however, it’s another situation entirely. You know what description you never want a woman you’ve slept with to apply to your sexual technique? “Baffling.