Most of the posts talk of moving the male pax away. An easier option I find is to move the UM's. Move them on some pretext (nearer to the galley where you can keep a better eye on them). However if this seating thing is such an issue why not block off one row until last minute which could be used for UM's? After all we're only allowed two per crew on our flights. If the row isn't used for UM's then you can fill it with those pax who are about to be bumped off due to overselling or staff standby's or last minute check ins.