Green’s Dictionary of Slang

(US) one who uses a great deal of obscenities; the obscene speech itself; thus potty-mouthed, foul-mouthed.

1969		Current Sl. III:4.
2001		‘Randy Everhard’ Tattoo of a Naked Lady 232: Do you kiss your mother with that pottymouth?
2008		T. Dorsey Atomic Lobster 107: You should have heard those potty mouths. Everything was ‘blow me,’ ‘bite me’ . . .
2016		Eve. Standard (London) 7 Nov. 17/3: There’s something winning about a potty-mouthed lady.
2022		J. Hannaham Didn’t Nobody Give a Shit 23: Her lawyer had coached her to curb her potty mouth.