My Pdoc is a former Muay Thai (Kickboxing) fighter, as well as having a laundry list of other martial arts he's trained in (seriously, if I ever needed a swift kick up the backside I'm sure he could kick me into next week ). I saw one of his fights on YouTube, that he'd won, and mentioned it to him and congratulated his win. He was a bit sheepish, but he thanked me, asked me to send him the link, and then we spoke for a few minutes about his fight career. He knows I found out about his martial arts background by accident, and I wasn't purposefully searching stuff out on him, so it was all good.