i can say first hand this actually works sometimes. this however will only work with a certain intelligence level. have to figure that out on the fly...
walk up. do no buy them drinks...
say "you know....curiosity killed the cat"
walk away.
at some point make yourself seen. maybe order a drink next to them. If they remember you they might just ask "what did you mean?" then simply say "nothing. it got you to to start talking to me though"
if smart enough they will realize hey.....they didnt do some average pick-up line.....like the ones stated above, lol