While you and a fat chick are in the water, have her bob down so only the ass of the girl is sticking out such to resemble a whales blowhole, you then stand on the side of the pool waiting to slay the "white whale" in the blowhole, finishing off with a dismount and inserting into whichever hole he pleases, Slaying the white whale.
The act of gathering the folds of fat on a whale's (particularily plump girl) stomach and then proceeding to jab them repeatedly with your penis, or 'harpoon', and then hollering "Thar she blows!" as you cum.
One night at the Ol' Slag, me mate,Ishmael, suggested that I "Captain Ahab" the bedraggled sea-whore beached at the table aft ours.