system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What would actually happen if you changed gear from 6 to reverse?

We all know the jokes about changing to R for racing on a highway, but what would actually happen if someone was to do that? Would the car break, explode, or nothing would happen because cars are idiotproof in this regard?
gpt
I used to work for an orchard and while a new person was learning the big sprayer they messed up. 

This tractor had a lever that was forward-reverse and a lever that was for gears 1-4 also had A-D gears. So when spraying you might be in B-4 with the throttle wide open. When crossing a gravel path/roads in the orchard we would have them pull the lever from B4 to B1 slowing down and being less bouncy. This was an electronic shifter that didn't need the clutch like A-D and Forward-Reverse needed. 

Instead of going from B4 to B1 he pulled the reverse lever. B4 forward to B4 reverse at 90% max RPMs. The seat broke the adjustment notches off and slid forward. Guy hit head on front window. Tractor didn't miss a beat instantly going from forward to reverse. We couldn't believe it. Nothing engine wise broke. It's been 5 ish years and still everything works. 

Should have demolished some shaft or broken a keyway pin on a gear -something.