Underwear growl Share definition Flag funny, clever term for the act of female flatulence. I just overheard my 4-year old daughter explain to my 6-year old son that girls don't fart, they have underwear growls. Underwear growl by lpyt2000 November 29, 2012 0 0 Get merch Get the Underwear growl mug. Buy Now — $32.95 See more merch