What is Sin Chin?
1.
Sin Chin: The abrasion a woman is left with after making out with some guy who didn't have the decency to shave his stubble therefore leaving her looking busted with a red-ass chin the next day.
me: "Yo, who you with last night!?"
skank: "Who? What?"
me: "You got sin chin bizzatch...tell that douche bag to shave next time!"
See