The opposite of a bidet, a bidon't is the act of spraying
water off of your ass and on to someone else in the shower. The best way to do this is by positioning a removable shower head between your legs and allowing the
water to ricochet off your butt-hole (and maybe a little balls or
gooch) and land on your shower mate. The perfect time to execute the bidon't is when your shower mate is washing their face as their eyes are usually closed so they are unaware of the source of the
water hitting their soapy face.
Bonus: If you have a hairy asshole, you can bypass the whole ricochet part by using your ass-hair as a filter, allowing the stream of
water to pass through the hairs improving the accuracy of your spray yet still achieving the "ass
water" effect.
Double bonus: If a dingleberry should happen to shake loose and act as a projectile, you achieved a level of bidon't that few live to tell about.