A guy I was training last night did something that surprised me.
It was his first day at the field, and, I think his 3rd flight of the day. He is a licensed pilot, and has had some sim time, so he knows his way around an airplane, it's just the finer details he's working on.
I showed him a few basic acrobatic bits because he was really handling the plane very well. The next thing I know, he points the nose straight up, drops the throttle, and does the prettiest tail slide I've EVER seen a trainer do. That thing droped easily 4-5 plane lenghts, maybe more, backwards before flopping over. He recovered easily.
I actually did ask did you mean to do that tail slide? If so, that was impressive, if not, lets go a little easier on the elevator

It was intentional.