What the heck?!

I was at lunch today, riding in my coworker's car on the way to Panera. We were stopped at a red light.

We look over and a semi has somehow managed to stop blocking the entire intersection. Let me just say if you're a truck driver you probably know when you can and can't stop.

Anyways, the semi starts reversing, which is fine. There is plenty of room between the semi and the Ford Ranger pick up behind him.

But the semi driver keeps backing and backing. Finally he rams the Ford backwards a few feet, pauses, and continues to reverse.

The driver of the Ford does not honk, yell, or anything. Instead he reverses a little farther back to give the semi space.

The light changes and the semi drives away.

I don't really understand what was going on. At all.