Have five guys leave the room. Set up two card table chairs with a sheet draped over them. Set chairs apart so a third chair could fit in the middle. Then have the girls sit on sheet and pull it tight. Bring guys in one at a time, explaining to them before they see the girls that they are in competition with the other guys to give their best pick-up line.
Sell it hard … “Everything counts — talk, walk, distance from the girls, etc.” Then just as they get ready to sit down, girls release pressure on seat, and the guy falls down. put a couch cushion on floor and make sure they don’t hit their head 😉