Stepmother tells me to cum while we are at drive though window and she rolls down window so everyone can see me cum!!

I am usually sitting in the back seat behind tinted windows beating off. We were at the drive though window at Carls Jr. when she tells me to cum, I start cumming about 5 seconds later and as I begin to cum she rolls down the back window so everyone can see me. Surely everyone turned to look as I was moaning and groaning like I am ordered to when I cum. As we pulled away my stepmother was laughing hysterically at me....