Nereida Gallardo, the hot girlfriend of football star Cristiano Ronaldo, has some characters tattooed on her lower back.
http://thesuperficial.com/2008/06/nereida_gallardo_still_wearing.php
I would assume there are more characters tattooed below her bikini bottom, otherwise the exposed portion of 戎友 means "armed friend", or in this case: "ass-guard".
It sounds like a punchline for some anti-anal-sex joke.
(Thanks, John)