Rumpback Whale

The act of breaching the water with ones ass like a whale breaching for a breath of air.

I gave the life guard at the public swimming pool a rumpback whale and they banned me for the summer.

by Hardly brothers July 27, 2009

Rumpback Whale

The ass-like crack formed by a fat lady wearing a tight bathing suit in the middle of her back.

That lady has a plumber's rumpback whale.

by Hhead August 30, 2013