Your cousin is a minor, worst thing that would have happened was he would have got arrested and released 6 hours later with no penalty. Basically just a slap on the wrist. He could have called you and had you pick him up at the police station and his parents would have never found out. And this would not affect his adult record. You are now responsible for everything since you signed the paper work. Doesn't make much sense that he pleaded for you to sign for him cause he didn't want his parents to know, yet says his parents would pay. If his parents are gonna find out when they have to pay, then why hide it and not let him get arrested?