Since you are relatively new, I'll explain.

It's called a reverse post, or just a reverse.

Someone posts about an encounter they had with some other person, then someone else posts (later) the about the same encounter, but them the perspective of the other person (pretending that they are in fact that other person who randomly happens to be on the same internet site as the guy they just interacted with in real life.

It's a CB thing.

But don't get too excited about them. It's pretty rare to come up with a good reverse. Usually they deserve a polite grimace at best.