In Lucy v$.$ Zehmer, the court ruled that under the objective theory of contracts

Since the writing was on the back of a receipt the reasonable person would not view the Zehmer was serious.

Since both parties signed the document, there was a contract.

Since both Lucy and Zehmer were drinking alcohol the reasonable person would not believe Zehmer was serious.

Lucy and Zehmer's conduct and language would be viewed by a reasonable person as a serious intent to contract.