This might seem like a silly question, but I've always wondered what submission moves actually hurt those involved? Obviously the ankle lock can easily be faked, but growing up I had my brother do the Sharpshooter on several occasions and it always hurt terribly. Now, obviously you can adjust for that, but was just curious which moves you know tend to be painful?
Both the figure-four and the reversal are notoriously painful if done in real life. Any of the MMA-based holds are of course painful. Although really, given that wrestling as we know it evolved from the "hookers" doing submission-based grappling back in the old days when you had to know how to make an opponent give up for real, it's not surprising that things would evolve from actual painful moves. Even simple things like a heel hook or kneebar were often used to break legs when someone was out of line.
I would of course be remiss in not bringing up the most devastating submission hold of all time: Big Bully Busick's stump puller, which was rumored to draw a quick submission 100% of the time due to Busick getting an erection while doing the move.