A derogatory phrase that implies the subject has an unclean oral orifice and uses said unclean orifice to perform oral acts with persons who may commit or have committed illegal acts or violence at sea.
"You shut your dirty pirate whore mouth! Yea, I said it."
As you're sticking your dick in a girl, you pull out right before you cum and squirt a bottle of Listerine up her cunt and then cum on her teeth, just because.
"So I was going down on this girl, and she had a really smelly pussy, so I had to give her a dirty mouth wash."