"Who's your friend? ... And how come not me?"

Make sure that the girl you´re hitting on is single because this shouldn´t be a pickup-a-fight-line...

"I may not be the best-looking guy in here, but I'm the only one currently talking to you."

"See my friend over there? He wants to know if you think I'm cute."

Funny line which will put a smile on her face for sure...

"So what haven't you been told tonight?"

You acknowledge that she has been getting hit on all night long and you do not wish to add to her frustration...

"Hey, I think we're like two banks: we both have interest in each other and we should merge."

Oldie but goldie. At least you get her to laugh... 

Source: Askmen