During oral sex the man pulls his penis out prior to ejaculation and cums on the girls face. He then pulls her hair down over her face, sticking it to the cum. Making her look like Chewbacca.
Bro, I just Chewbacca faced my girlfriend.
When a man is having sex with his partner and proceeds to blow his load on her face, then yanks out or cuts off his pubes and throws them on her face making her hairy like chewbacca. If done by a "fire crotch" it could be mistaken for an ewok.
My mom walked in while giving my girlfriend a chewbacca face and we have not talked since.