Skipping a field trip? ?

K. I joined some army **** for after school activities. I really hate it and tomorrow, they have a field trip to their HQ; we're gonna be there for 12 hours. I can skip it if I come to school at 750 (school starts at 720). The problem is, I have no where to hide and if I come at 750, they're gonna call my parents. Where should I hide, and if they do call my parents, what should I tell them? :/. If it helps, there's a shopping mall right opposite my school. I really, need to skip it so don't be an *** and give me retarded answers. :)