It's pretty rare that I'll make a serious effort to get in a girl's pants (I don't really care enough, under most circumstances), but my friends and I will come up with fake backstories for ourselves before going out all the time. The funny thing is that it usually works.
One of my favorites is to simply switch all our names around, and pretend like we're from out of town.
Me: "Hi! I'm Bay. This is my friend, Greg! We're in from Atlanta. What's fun to do around here?"
Other friend: "Hey!"
*Flirtatious small talk ensues until Other, other friend who went to the restroom walks up*
Me: "Hey! I'm Bay! What's your name?"
Other, other friend: "Hey! I'm Chuck!"
Me: "Hey Chuck! We're from out of town!"
Other, other friend: "Nice to meet you! You guys want some shots?"
Me: "Sure man! People here sure are friendly!"
*Aside to girls as soon as he leaves* "What a weirdo, amirite?"