This may be one of the most impressive posts I've ever seen, Yoda. Pulling your chest to the bar with an extra 15 pounds? Few people can do that for a single rep and no weight, and you did it for three sets of six!
Impressive as heck.
I used to have a student in class who could do it easily. He was tall and lanky with long wiry arms. I had so much fun with him, I'd holler at him to get higher (with no added weight) and no kidding, he would pull his abdomen to the bar. He was chinning machine like I'd never saw before nor since. Thick glasses, nodded yes anytime I mentioned something and never failed to give 100%. Always wondered what happened to him.