Cook bacon . Place a small but tempting piece on each of 3 or 4 plates, put the dog outside (!), place plates on the floor leading from your teen’s room toward the bathroom. If necessary, wave the bacon near his/her nose.
Borrow the neighbor’s puppy (you don’t want your own puppy, you have a teen!) and put it near your teen’s face. Licking will probably do the trick. If not, the puppy will soon pee on your teen and that should work.