Cock
From wipipedia.org
Cock is a vulgar, and some would say, obscene term for penis. It's suggested to be approximately as obscene as cunt, but most men are quite happy with calling their's that (as are women, actually, vis-a-vis cunt). The uninhibited dictionaries tells us its derived from Old English cocc (rooster), reinforced by Old (and modern) French coq rooster, penis. See penis.