Someone with exceptionally vulgar language. Swears are said at inappropriate times, out of context, and in front of children, authority figures, and clergymen.
Dan: Maria is throwing around f-bombs in front of her boss! What a port-a-potty mouth!
Connie: I was walking the fucking dog and then the piece of shit starting humping a fucking geezer! Can you fucking believe that shit?!
Maddie: Wow, mommy, you have a port-a-potty mouth.