Jen tells her professor Dan that if he performs his torts rap in class a second time that she would give him a perfect rating at the end of the final exam. Dan then puts on a show complete with backup dancers and T-shirt cannons. After seeing the performance, Jen thinks it was good but not great, and she decides not to post a rating online after all. If Dan sues Jen for breach of contract since he fully performed, what is Jen's best counterargument?