Wow, you guys are fierce hahaha
I'm a little unclear about the title, "your girl" so I'll just provide two ways.
If the girl is your girlfriend and this guy is just hitting on her like a woodpecker banging the tree, I'll step right in and say something like "hey, baby having a good time?

" Most likely she will give me this look, whether she is or isn't comfortable, whichever one doesn't matter because I would then look at him and introduce him as her boyfriend and greet him by shaking his hands. I will smile, I will treat him like another human being. I will look at him in the eyes and give him the warmest, understanding smile ever. Why? Because like us he is just another guy who is looking for that girl and maybe he doesn't know that she is your girl, so I personally don't think it's his fault. This will also psych him out, because I'm not reacting so aggressively or hostile. I'm friendly and warm, which will leave him on his toes and at the same time comfortable, like a lion purring at you while looking you straight in the eyes instead of getting ready to pounce the shit out of you. After all of these greetings shit, I'll probably ask him, "hey, man how are you? Any cute girls tonight besides this one?" *pointing to my gf* and laughs. He will probably laugh too or he doesn't, doesn't matter, I'm having fun and semi-fucking with him, but I'm being nice about it, so......

haha
If he says yeah or no or whatever it is, I'll probably chat with him along with my gf and just chill. Why shoot a guy down when you can possibly make a friend and have this friend blocked other guys that possibly hit on your girl? Once I make this kind of friends, I don't always have to be there with my girl, he helps me out by guarding her when I'm not there, because I just accepted him. Heck, I'll even let my girlfriend be his wing girl if I want.
Okay that was for girlfriend, here's someone you're meeting and there's this guy hitting on her while you're just vibing with her. You do the same shit but this time don't address your girl as your girlfriend. You look at your girl, call her by her name, "hey Jen" or whatever it is. "Having a good time tonight?" You take her hand, look at her flirtatiously, hug her, whatever that shows intimacy or affection and then you pause and look at that guy, if he's still there, and greet him, introduce yourself, and do the same thing as above. Shake his hand, become his friend, talk to him, make him feel comfortable and shit, because most likely he's probably not feeling comfortable and he's out like all of us just trying to find a girl to meet. And like us, we don't want to deal with assholes bfs or aggressive guys, so why not do him a favor and just give him a break. I learn to appreciate and respect those kind of guys the most because he's composed, cool, and just a fun loving guy. That kind of guy is kinda scary because he doesn't even seem threaten and affected, he knows he can fuck that other guy up but he doesn't, it's not worth the time, the energy, and the aggression. That other guy is small fry, that warm loving guy has bigger problems, he's just here to have fun, so when he sees another guy, he doesn't look at him as a competition, because that's just a negative way at looking at a fellow guy. He sees this guy as a guy who's just like him loves women and wants to meet them. He appreciate and embrace this fact and befriend him. I would hate to look at all of you as competitors trying to steal my girl away, and I know you guys are all respectful. So just chill and have fun, and be cool
- Nelson