I would add:
Shit head: a negative term for a person who likely is toxic or caustic for other negative reasons
Shitter: a person who may enjoy shit head humor. One who shit is not necessarily negative like shit head. Could be used to casually downplay a type of humor (lightly positive) or to dismiss a type of behavior (lightly negative)
One day, this too will turn to shit. But when that day comes, people will just drift to different instances. Not including federation and niche communities, this is functionally equivalent to reddit for me