When women don't follow through with bets

[SenorSuave]

Ok, so here's the deal.
Today we had a thing at school called class day. I gamed an HB I'd known and used Style's Five Questions game on her. I bet on a drink. After winning without a problem, she didn't follow through. How might I go about this to guarantee I get my end of the deal?

 

[theunflushables]

Kind of joke about it once or twice, if nothing comes of it, drop it.

 

[jt the azn]

Use reverse psychology. Say that you don't want her to buy you a drink anymore. Make it sound like you don't give a ****. Then, she will want to buy your attention back.

 

[GaryUranga]

smack her

 

[Grand Wizzard Alamar]

The problem is you might sound desperate asking for it (it's just a drink) but you sound weak if you let her push you around.
I'd act annoyed around her, and note that she was unfaithful to her part of the bet, making her worth as untrustworthy for any future agreements.