What excuse could i use?

Im going to bamboozle from ny on may 1st with my friend in my car for the day til 1 a.m wed get home. im 18 so technically i dont need my moms permission but she would not let me go without an `adult` so im sneaking. but itll be fishy since we wanna leave early and my tickets should be coming in the mail soon. im gonna be on vacation but my moms home... help