I've recently read several post wherein people expressed concerns about testing there art and new skills with friends, etc. I'd like to tell this short story as a lesson to all those who might want to do this.

I guy told me that he could get me in a hold that I couldn't get out of. I took the challenged and allowed him to jump on my back, put me in a choke hold and wrap his legs around mine. I tried to throw him and landed on my head with him on top. Guess what, he was right, I could not get out of it. However, I learned a valuable lesson from this and have not allowed it since; NEVER ALLOW SOMEONE TO GET THERE HOLD ON YOU. Once they start to make their move then react immediately to prevent them from securing their hold. Many years later I had a similar situation occur during a self defense seminar wherein a lady tried to embarrass me by attacking me very aggressively from behind. I did not allow her to complete her move and shoved her off me pretty hard. I did get scratched on the neck from this. If you LET someone get there hold on you then it's going to be a lot harder to prove your abilities.

I agree. I hate when people try and prove you wrong or embarass you when you are trying to help them.
A few years ago we were giving a demonstration when a rather large athletic guy was giving my friend a hard time when he was showing a wristlock during the hands on.
The guy basically put a death grip on his wrist with all his might so naturally the lock didn't work.For those of you who don't know they don't work that way exactly,especially if your opponent is stronger. I had him grab my wrist when he did I politely slapped him with my other hand and went into the lock from there. He was a little nicer after that.
You are right,never give them the opportunity to embarass you.

I agree I accidentally applied a choke well not really a choke but more of a really agressive grab with a knife on my instructor a little too hard while doing a demonstration to the class. Boy does that guy know how to get out of those he didn't even hit me with his own hands.

Here is what happend: I grabbed him from the side with my left arm wrapped around his shoulder locking his right shoulder in my arm pit, then I took a knife and put the point to the left side of his throat. That was my attack.

His defence was he smacked the back flat of my hand (the one holding the knife) behind me, grabbed my tricep and threw my arm into my face. Geeze I never fell so hard in my life I thought he ripped my head clean off. Good times, good times.