Rolling pitstop

"Ugh, just as I was starting to like you." Pete says, almost hurting your feelings, but somehow making you more horny anyway. "If you need to go so bad, just stick your ass out the window and go."

You can't really think of much fault with the plan, mostly because you're too fucked up to think rationally. Probably get some on the side of the car, but it'll wash off with rain. Better than getting it soaked into the seats, and Pete clearly has no intention of stopping.

You quickly relent, drunkenly stripping off your panties in the confines of the car, then hanging your tight butt out the window. You cling for dear life onto the handles above the window to keep from falling out as your brother speeds down the highway.

You feel a bit self conscious about letting other cars look at your exposed pussy and asshole, especially while you urinate, but your intoxication makes you find the whole thing thrilling. You have to go pretty bad at this point, so you let loose.

The wind catches your stream immediately, splattering the majority of it along the rear passenger window, with the rest turned into a fine mist that blows back into your face. Your brother laughs, not getting much on him himself, and throughly enjoying the spectacle.

You giving yourself an impromptu golden shower by pissing in the wind doesn't really bother you much in your current mental state, so you don't let up, even though you're getting soaked. Several cars honk and shout at you excitedly.

The car begins to slow down at the same time as your stream slows down, and by the time you're letting out the last trickles, you've come to a complete stop. You look around to notice your asshole brother stopped at a rest stop anyway, and has begun honking and shouting at nearby people to look at you.

A scummy looking guy hanging around the rest stop for piss whores takes note of you and rushes over to manhandle your exposed buttcheeks. Your brother offers to let him fuck you, and you make no effort to complain, even wiggling your rear tantalizingly for him while he begins to gruffly stick his fingers in you.

Needing no further invitation the man inserts himself into your pussy for a quick lube up before fucking you in the ass. He trades between your holes several times as you both get more into it. Your brother watches and begins slowly getting aroused again from tricking his sister into fucking some weird stranger at a rest stop.

The man begins pumping faster into your asshole, finally finished with the switching routine of enjoying your holes and working up a rhythm. You near orgasm immediately, and the stranger doesn't seem far behind.

"Go ahead and cum in her ass! She doesn't want the dose." Pete shouts over top of you. You make no effort to correct him, since for the first time you can think of, you don't care about swallowing the dose.

You and the strange man begin to orgasm at the same time, prompting Pete to slam on the gas pedal. The man dislodges from you as your ass begins speeding away from him. The first shot of the man's wasted dose hits the piss soaked rear window, leaving the rest to splatter on the concrete as the car disappears into the distance.

Pete laughs hysterically at getting to fuck up both your orgasms at the same time. You want to complain, but find your throat full of your brother's hard cock again before you can utter a word. Within seconds you've forgotten about the trick entirely, now trying to find the rest of that orgasm you nearly had by ramming your face repeatedly into him while masturbating once again.

"We're gonna have such a great day together, Sarah! Just you wait!" Pete says, holding your head down to keep you from sucking him off too soon.