“M-E-N-S-T-R-A-T-I-O-N.” No dude, that’s not how you spell menstruation. In a new video, BuzzFeed asked five guys to explain how periods work and the results are undeniably funny. Armed with a pack of menstrual pads, a box of tampons and a drawing of the female reproductive system, the dudes hilariously try to figure out what's going on down there.