I though of this opener te other night and tried it quite a few times and it works a treat.
You approach a set 3 at least and ask which ones the leader of the group. I found around 80% of the time the hottest one will be "voulenteered" at this point you hold out your hand and tell her you new to borrow her for 2 minutes (it's all you need to buy yourself the rest of the night) take her to the bar and do a tequila shot each then begin multiple threading from there.
I've found on numerous occasions I get the strong IOI of "oh my god! Tequila make me soooo horny!" best feeling
Troubleshooting:
1. If the group do not designate the hottest girl as the leader then simply get the "leader" do give you a voulenteer. Just lead her to the girl you want
2. If met by resistance when asking the girl to follow, she simply needs you to take responsibility for anything that may happen. All you need to say are the words "don't worry, it will be fine, trust me" (thanks AFC Adam)
3. For anyone that doesn't believe in buying girls drinks if she's not worth the price of a shot then why are you trying to pick her up??
Tell me what you think guys. Love to here some field reports