Had a '67 Nova SS with a 283 and Powerglide tranny. Was cruising down the highway at 60 mph one day and my (now ex-) wife "knocked" the thing into reverse. To be fair to her (it's not the reason she's now the ex), the shift lever was in the center and the spring for the reverse lockout had broke, it was an incident waiting to happen.
Anyways, heard and felt an almighty clunk, and things became strangely silent. Looked in the rearview mirror expecting to see bits of transmission, or maybe the entire thing. Might have been a little puff of smoke, but that was all. I'm coasting downhill with a dead engine, trying to figure out where the best place to pull over might be. Nowhere within a mile, so I put it in neutral, restarted it, and kept driving.
The ex never said a word the rest of the trip. Best drive I ever had with her in the car.