Contracts, Part II: Consideration, Legality, Consent

A waitress claims her manager told the waitresses that whoever sold the most beer during the month would have her name placed in a drawing, with the prize being a new Toyota. She was told she won and was led to the parking lot blindfolded. What she found was a Star Wars toy Yoda. She did not find the humor in the manager’s actions and filed suit. Does she have a case? What theory should her suit be based on?