A quick pit stop

A few hours into the trip your dad needed to stop at a service station to fill up before they could continue on their journey. As soon as the engine was turned off you and your sister were of to the bathroom to fuck.

“Be back in 10 minutes!” Your dad shouted.

You all but ran to the bathroom and into one of the stalls before locking the door and pushing your lips together.

Robin pulled back slightly and whispered “put it in my ass”

You smirk and whisper back “as you wish” as you reach down and pull her panties down slightly and turn her around so her front is pressed against the stall door.

In an instant your cock is out and penetrating her tight back door. Robin moaned and pushed back into you.

“Fuck yeah babe. I love your hard cock in my ass. Pound me hard and fill me up real quick or else dad will leave us.”

You didn’t need words to answer that, just the sudden sound of rapid skin slapping against skin and the moans of your sister folding under your might. Robin was right, this quickie had to be quick.

And quick it was because after 2 minutes of fucking you blew straight into her tight ass, which in turn caused her own orgasm. After it subsides you scrape some of her juices from her legs with your fingers and stick them into her mouth, which she happily sucks off.

You pull out of her and put your cock back in your pants before giving Robin a quick peck on the cheek as she's still pressed up against the stall.

"Clean yourself up. I'll go get some snacks and meet you back at the car." You tell her before leaving the restroom.

You leave the bathroom, pick out some of your most favorite snacks and take them to the counter,as you set them down the cashier looks at you knowingly.

"You have fun in there kid?" She asked "Let me guess, sister?"

"Yup, she's the best."

"Yeah, I started dating my brother when I was 15. Best decision I ever made. He's my husband now."

"We're probably headed the same way, just waiting till we finish our education."

You continue the small talk as she rings you up. You pay her just as Robin comes out of the restroom, you link hands and head back to the car. Even though it's subtle you can tell that your sister is walking with a bit of a limp from the rough pounding you just gave her ass.

"You actually made it back. Let's go." Dad said with a hint of surprise.

With that you get in the car and carry on the last few hours to your uncle's.