My step-Mom, step-Dad, step-Brother and I have been on a road trip for the last few days. I was listening to music while we are stopped at a rest stop when I see my step-brother trying to get my attention. I pulled out my headphone just to hear him talk about how horny he is... I told him it wasn't my problem but he just kept bugging me about it. He begs me to show him my tits but I remind him I'm his step-sister. He doesn't seem to care and keeps bugging me. I cave thinking that'll be enough to shut him up but after I show him he pulls out his cock. step-Brother had way bigger of a cock than I expected, it started making me wet. My step-brother asks to see my panties which I thought to be odd. He then asks if he can smell them. I let him so we could get this over with. step-Brother asks me to stroke him so he can cum which I hesitated but caved again. I know we are running out of time before our parents get back so to hurry things along I suck him off. I tasted my step-brothers cum and I'm still not sure how I feel about it. He begs to feel the inside of step-sisters pussy so step-brother slid in his cock. step-Brother was still fucking me when I saw our parents start walking to the car so I told him to hurry and just cum inside me so there wasn't any mess.