milwaukee mustache Share definition Flag Giving oral sex to a female during their ovulation cycle, thus leaving a red "mustache" on ones upper lip. Bro, my girl was on her period lastnight when I ate her out, and left me with a Milwaukee mustache! milwaukee mustache by Agent_Hollywood January 2, 2018 0 0 Get merch Get the milwaukee mustache mug. Buy Now — $32.95 See more merch