Bathsturbate
When a person masterbates while they are using the bathroom
"Kelly is such a bathsturbater! I mean she masturbating in front of me while she was peeing!"
Bathsturbating
The act of masturbating while in the bathtub.
"Dude, did you see that video that was leaked of Brittney Spears bathsturbating?"
"Yeah, dude, that was revolting!"
"Yeah, dude, that was revolting!"