Spot the girl you like and implement the three second rule, approach from the friendly angle (not head on) at quite a rushed, deliberate pace. Once there you should have her attention, so raise your eyebrows and break into a prolonged smile naturally. A relieved smile. Then confidently open with:
PUA: "Hey, could you do me a rather big favor?"
Target: "Um...okay, sure I guess. What is it?"
PUA: "Oh, it's okay. You're already doing it"
Target looks puzzled for a moment
PUA: "My nutter of an ex girlfriend is here so I'd rather be busy doing something than just plain avoiding her"
See where your target takes the conversation. Either you'll get talking about Exes and how inconvenient they are, or the Target will put up a bitch shield/set up some banter. React to it.
PUA: "Seems like you're a little jealous that a screw-loose hasn't gone out of their way to try to speak to you"
Target: "Apart from...you?"
PUA: "You can be as clever as you like, but you're still doing me that favor.
If you do this with the right degree of confidence and with a smile your target will laugh or at the least smirk. Irrelevant of the response (unless it's something you feel confident can result in a good conversation bridge-builder) move the chat on by saying something along the lines of:
PUA: Come to the bar with me, [then maybe you won't look so bored]. I'll buy you a drink to say thank you - this is a favor that doesn't have to end just yet"
And there's your opener. I even included a Neg in square brackets there if you feel comfortable deploying one. It's not perfect yet, but it's a good start. What do you think?
