Hm. I was quite lucky to only have one such encounter. It was some bot inviting people with a certain prefix in their username to a chat, posted one link and then was silent. The group of 50+ people then decided to repurpose the chat to be for an honorable committee, making plans to freeze the world (fighting global warming), throwing a nuke at a bright house of a (at that time) high-positioned person in the USA, overthrowing the danish government (idk why or who started it) and some more stuff.
It even spawned a subreddit :))

It was a nice chat group actually, though with time, many left. I think it might be barely over 20 people left now, and no one's said anything in a few months now.

I think most of my followers are bots though.