whale tail

whale tail
 n.— «Even though I work out in a thong, my G-string always remains discretely tucked beneath the waistband. Despite my love of the G, I hate when girls let their “whale tails” creep out of their paints—I’d give out citations for that offense, too, if I could.» —by Jessica Kaminsky I Hate the Gym Dec. 28, 2004. (source: Double-Tongued Dictionary)