In a class action lawsuit, were the class to win, you could recieve your portion of the money by proving you had the coupon in your possession prior to the lawsuit's filing. This would be hard to prove, but nonetheless possible.
She has to sue for $114Million because each person in the class action suit only gets a percentage based on the win. If only 2 people end up "being in the class" they don't split the $114 million... they will get however much the drink was worth (probably a couple bucks).
The $114 million pricetag is based on the estimated number of possible plaintiffs in the class action suit.
I'm not a lawyer and this isn't fact, but it's my educated guess. Feel free to tell me I'm wrong. It's not like this person spilled hot coffee on themselves and wanted $114million.
In other news, your mom eats butts.