A 14 year old classmate was in a terrible accident and became quadraplexic. I never hung out with him but knew his name and was friends with friends of his. I felt so terrible of course and even suffered chronic anxiety about it at the time. A few years later, at 18, an acquaintance who I was uncomfortable around because he didn't take hints very well that I didn't want to hang out was telling me about how our old classmate was and mentioned how her arms would jerk up suddenly and I suddenly started laughing. It was a ha! Type of laugh rather than a full on crack up. It was pure nervousness but by that age I learned to deal with my general and social anxiety with laughter to calm myself but I don't usually don't do it at inappropriate times. I was even shocked that I laughed. My friend was nice about it but I'll always think about it and wonder how I could be so retarded. I assume it's due to an acute feeling of stress/anxiety around the situation which makes it hard to think clearly and not be reactive. There are so many cringe things I've done socially in my teens and twenties that I don't even bother keeping in touch with people in my high school. I was just too nerdy to focus on social skills for too long. I needed a better approach then going into fun and goofy mode like a programmed robot in social situations unable to adjust my sails when something serious is discussed with a distant acquaintance.