Are you talking about the "Mock penis"?
From wikipedia:
A mock penis is the clitoris of the female hyena. Prior to sexual intercourse or when sexually excited, the hymen swells with blood. It hangs out of the vagina and ironically resembles a penis. Biologists have reported incidences of these "mock penises" being larger than 15 centimeters in length and 10 centimeters in girth.
( http://en.wikipedia.org/wiki/Mock_penis )
