Question: Tina Muller applied for a loan with CES Credit Union so that she could buy a car from her brother, Joseph Muller. They both signed the loan contract, Joseph signing as a co-signor. It was two months before Joseph's 18th birthday. The loan was approved, so Joseph transferred the car to Tina. When she defaulted on the loan, CES repossessed the car and sold it for less than the loan amount. More than ten years after Joseph co-signed the note, CES sued him for the deficiency. He tried to disaffirm the contract. Could he?