Concert public sex

A few years ago, I was at a concert. At my bf request I wore a short skirt and a tight shirt, no bra. I wore a tiny thong and heels. His dad drove us there and I was in the backseat, I could see him checking me out in the mirror, but pretended no to notice. At the concert my bf went to get drinks and a cute guy came up and started rubbing my ass though the thin skirt. Casual at first but when I did react he got more aggressive . I felt him lift my skirt and start ******* my ass with both hands. Other guys started getting closer and taking pics. Suddenly I felt his cock grinding between my cheeks and others hand ******* everything else. I felt his hot cum shoot over my ass and coat me. He walked away, and I turned to see my bf watching me. I thought he'd be pissed but never mentioned it, on the ride back, we were both in the backseat and he had my thong off before we left the parking lot, his dad saw plenty. And as I got home I made eye contact and winked