I mean although cock is rare I can think of 5 films right off the top of my head (Brown Bunny, Bad Lieutenant, Forgetting Sarah Marshell, The Watchmen, Boogie Nights) no problem and I know I could think of some more. Where as with vag Basic Instinct is the only one for sure, don't remember if Species had vag in it. But breasts are almost the only thing shown most times b/c vag is kinda offensive to a lot of ppl as is cock. Plus in our society we worship the female body much like Greek and Roman society worshiped the male body.