From the French expression " il ne dormirai pas dans la baignoire " ( he don't gonna sleep in the bathtub )
suggest that a man is really attractive ( sexually and mentally) and if he have to go at your home and stay a night , he don't sleep in the bathtub but you expect he have sex with you a lot of time.
Bathtubable is more classy than fuckable
James is absolutely bathtubable