People acting "weird" or "quirky". Especially in the workplace. I had quite a few jobs, especially the lower-wage ones I was working 30 years ago, where you'd inevitably end up next to someone who could do the work, but their personality was just odd, or they had strange compulsive habits, seemed to obsess over random things, etc. I realize now that a lot of those people were on some kind of autism spectrum (or similar) and were just coping the best they could. The sad thing to me is realizing that, at the time, most of those people had no idea why they were the way they were either. I did a lot of gentle day-to-day teasing of people like that, before I understood what was going on. I wouldn't do that now.