Don't forget to tap!
My family and I visited New Zealand in 1980 at the invitation of a local Aikido instructor. I taught classes at his dojo for about 6 months. New Zealand is a beautiful country with very friendly people.
One day I was teaching a group of constables from the local police station. The detective sergeant in charge asked me to be careful not to injure them. I tried very hard to comply, and lectured them clearly to tap out as soon as they felt pain, and to release immediately as soon as they heard a tap.
The constables seemed to like sankyo a lot and considered it to be very practical for their work. So, we did a lot of sankyos from a variety of attacks.
I selected the biggest constable in the class to demonstrate the techniques on. They said that he knew some Aikido, so he seemed to be the perfect choice.
I demonstrated a sankyo on him very lightly at first using about 10% power. No tap.
OK, so he has strong wrists. I cranked it on again, this time with about 30% to 40% power. Still no tap.
The third time I really let him have it with about 60% to 70% power. He jumped up into the air screaming. The rest of the class was uneventful.
I didn't think anything more about this except to be surprised that the guy had such strong wrists. Right?
A bunch of us went to the pub that night and this guy showed up with his wrist all wrapped up in an ace bandage. I was astonished and asked him what happened.
His explanation was that the FIRST time I did the technique it hurt so much that he went into shock and couldn't remember to tap.
An interesting bit of trivia about New Zealand is that the police have pubs inside their stations (at least they did in 1980). The constables seemed to like me and invited me to their pub on a number of occasions. It was actually the best one in town.
After partying with these guys I did, however, wonder how some of them were able to make it home OK. But then, I guess they weren't worried about getting busted for DUI.