Looking for advice for incorporating the Benjamin Franklin effect into my game.

Benjamin Franklin Effect

I've seen this work naturally, but I would like to ask for examples for more ways I can ask for little favors that lead to bigger ones.

I'm going to try and challenge myself to get a girl to buy me a drink this weekend and see if it leads to something else

TL;dr How would you go about using the Ben Franklin effect to get a drink at a bar from a woman? Got any generally good Ben Franklin games/scripts/frames?