A condition of the post coital female vagina whereby it is rendered cum filled and oozing ejaculate down to the ass crack. Oyster Slick vaginas are great for cream pie lovers and those that love sloppy seconds and thirds or more, especially in a gang bang session.
Roger and his friends pulled a train on his girlfriend Friday night. To say the least the tenth dude to nut was getting a true Oyster Slick.