Just a few things that's happened to me lately. For instance, an older man (sixties I'd say) started chatting to me in my gym class, and I couldn't really be bothered chatting back, so just answered in one word answers and walked off when the class started. He then spent the class glaring at me, doing his circuits right next to me and then did the same thing in the gym afterwards. I don't think I was especially rude, I just don't chat to people at the gym.
Ditto a couple of older men of I'd guess a similar vintage online, friends of friends on FB and on another forum I use. Sent me pms which I ignored and then started making comments about me being snooty etc on posts visible to me. Actually quite a bit of nastiness about it.
I'm trying to imagine if I got arsy with a young guy 25 years younger than me for not engaging with me in similar situations and failing.