lip bum Share definition Flag When someone doesn't know it's actually called lip balm, they call it lip bum. Don't ask me why they do it, they just do. Billy: Why do you wear lip bum? Mel: IT'S LIP BALM YOU IDIOT. lip bum by cheesefanatic July 2, 2017 0 0 Get merch Get the lip bum mug. Buy Now — $32.95 See more merch