The act of performing oral sex on a woman with a mouthful of chewing Tobacco while she is menstruating. The individual performing the oral sex may not spit out the tobacco and must hold it in their mouth or spit inside their partner.
If performed correctly The individual will have a reddish brown mustache and/or goatee from the blood mixing with Tobacco spit.
Hence the name "Red Man Mustache"
Did you hear that Lee got himself a Red Man Mustache the other night?