Pissmate

2 or more individuals who Piss at the same time everyday.

John: Did you know Jessica is my pissmate?
Mike: Woah! that’s nice dude, i wonder who my pissmate is..

Shitmate

2 or more individuals who shit at the same time everyday.

John: Hey, did you know Jessica is my shitmate?
Mike: Woah! that’s cool man.