Oxford English Dictionary. Scatology. 1. That branch of science which deals with diagnosis by means of the feces.
2. That branch of palĉontology which treats of fossil excrement or coprolites.
3. Filthy literature
Scatological. Of or pertaining to scatology; characterized by a preoccupation with obscenity.
Wikipedia. "toilet humor"; off-color humor, a.k.a. vulgar humor or crude humor