If you pass gas on there face is one. I watched a person do this and it totally killed the mood. Basically any trivial little act that a total wimp would get offended by will send a girl running. I'm not saying what I mentioned earlier was small, I'd get to swinging if that was done to me but girls will run away for a lot less. I've seen a girl reject over a noninflammatory joke before. I've seen girls walk for virtually nothing.
I hate guys who act like they're all big, who will flirt with other girls behind your back when you're together, who lies all the time, who smells bad all the time, who doesn't pay attention to you at all, who won't call you or text you each day to check up on you, who will always make up an excuse to go somewhere, who always gets into trouble, who just wants sex, who judges other people, who will be man enough to get a girl pregnant but then leave her hanging, who doesn't know how to keep anything clean or organized, who fights all the time, & who always runs his mouth.
Poor hygiene, gross habits (chewing with your mouth open, belching and not excusing yourself -- hey, I belch with the best of 'em, but if you're with someone else at least excuse yourself -- and clipping your toenails in random places), being stingy (with affection OR money), paying more attention to your truck/car than you do your girl, checking out other girls while you're talking to us, and being stuck on yourself.
Taking a shower in axe...and I may be shallow for this one but jacked up teeth is really unattractive to me. And the usual cheating and whatnot. Drinking to much is a turnoff for me... Or anyone who gets drunk more than once a month...