When I was in Junior High, I broke my right arm... broke the tip of the radius off, had to have it pinned for a number of months, then they unpinned it, and I had to learn how to use my elbow again. As a result, my right elbow has a ton of scar tissue built up in it and I do not have a full range of motion. I am missing the last 15-20 degrees when straightening the arm. Also, that elbow is very stiff.
When people put an armbar on... my elbow is stiff, its gets much stiffer as it reaches the end of its range of motion... and if it goes past the range of motion, while it hurts... its technically good for me, as it is breaking down the scar tissue in there, helping to give me a better range of motion.
The problem is that people get used to how my right arm feels... and then go after my left arm. My left elbow is very loose, straightens all the way and if you go past its range, its a break or dislocation.
To protect my left elbow, whenever people go after it... I tap as soon as they isolate the arm. This surprises many people when I roll with them, because they usually know that I have a very high pain threshold. I just am not willing to trade my good elbow... I would rather tap, and try again. This leads to me tapping out in all kinds of weird situations... but its my elbow and my ego.... My ego is good with tapping and my elbow still works as it should....