My idiotic (and drunk) friend thought it'd be funny to steal my car while I took a ****. He drove around 100 feet before he realized that he was too drunk to drive, so he decided to stop. All of a sudden, I hear a sound like a jackhammer. "DUDUDUDUDUDUDUDUDUD" coming from my poor car.

It turns out, he tried to put it into neutral (god knows why) and somehow managed to put it in reverse. He was going maybe 15-20mph, and the act of slamming it into reverse stopped it pretty damn quickly. The tires never chirped or anything.

Anyway, what sort of damage could this do? The transmission seems to be running fine, no jerky shifts or weird starts.

im not a trans expert but i know it aint good for em i did it by accident once and it shut my car off and engaged in what felt like neutral..Never did any harm this was on my last buick

Don't worry about it! I have done MUCH worse to weaker transmissions.

A quick Googling says that your transmission is either feeling fine or self-destructed.

Lesson learned: your friend should be the designated driver from now on.

If he says your safe, then your safe. Just don't do it again.