I almost went ahead and used this one, thinking it might be ok because it's just a sillouette, but I don't want any trouble:

https://www.modelmayhem.com/pic.php?pid=1616396

One of my favorites, definatly 18+, I feel lucky that MM allows males to post nudes at all:
https://www.modelmayhem.com/pic.php?pid=1269923