Yarn Martyr

A person whose annoying or derision worthy behaviour actually has a net positive effect on the receiver, by providing them with hilarious stories to share with their friends, despite the actual encounter remaining annoying.

This person is actually (usually unwittingly) sacrificing themselves for the stories of others, by offering to take the role of fool.

This guy at work used to be the biggest jerk, but now he's transcended jerk and become a yarn martyr, so at least I get these great stories out of having to put up with him