Used for women who refuse anal, or just because it's hot. While the girl is face down while you are ramming her from behind in her vagina, in mid-pump, you come down with a judo chop to the head but keep your hand on her, forming the shark fin. It should be of sufficient force to knock her out. After that, you put it in her ass. Hence the tail.
My girlfriend refused to try anal with me so I gave her the Fernandina Shark Tail.
by BadAssJimmyB August 05, 2009