1) When one drinks a Bloody Mary too quickly, causing the horseradish to stick to one's upper
lip, creating a mustache.
2) The residue or anal hair on one's upper
lip resulting from performing
oral sex on one's woman from the rear.
eg 1) "Hey Mike, them
boys are drinkin' your Bloody Marys so quickly they gots them some horseradish mustaches! Yee haw!"
eg 2) "Dude, had a terrible
night last
night. Christina sat on my face and made me go down on her. Ended up with a horseradish mustache."