Scottish Beard
The residue left on a person's mouth area after giving oral sex to a girl during her period. Named so because it looks like the person has a red beard.
Guy 1: "So I see you went down on your girl last night."
Guy 2: "How can you tell?"
Guy 1: "You're rocking a Scottish Beard, bro!"
Guy 2: "How can you tell?"
Guy 1: "You're rocking a Scottish Beard, bro!"