Jonah is 12 years old and absolutely loves soccer trading cards. At the local hobby shop, he finds a "Lionel Messi" trading card in the case, which has a handwritten tag by it that reads "9/00-." The employee at the front desk interprets this to mean $9.00 and sells Jonah the card for that amount. A few days later, Ronaldo, the card shop owner calls Jonah and asks for the card back because it is worth around $900. Jonah refuses, and Ronaldo sues. what is Jonah's strongest argument?