i'll admit, i tried this once or twice way back when. terrible idea. it was kind of a neat sensory experience, but once it breaks open it is just an awful mess. i am glad i lived in a campus apartment, and when the bath drain was clogged from it, they had someone fix it right quick.
cloth ones though, i always do this. it's the easiest way to wash it out quickly, since i don't wear cloth often and i don't want it sitting around, waiting for laundry day, smelling like stale pee.