slanty bum Share definition Flag When a female has straight back with little to no ass at all. The ass appears to be one with the thighs. Judy had a big booty but Sarah has a slanty bum. slanty bum by byrdmanjenkins April 4, 2015 0 0 Get merch Get the slanty bum mug. Buy Now — $32.95 See more merch