I got banned from a turbine server for joining it. Apparently I wasn't allowed to join it or something, so instead of setting a password, they just banned anyone that joined the instant they connected.
I also got banned once for hitting a headshot on a person that was "in spawn". To be fair, that headshot was bullshit, and probably the worst case of lag I have ever seen. If I remember right, I ended up shooting at a soldier, and missed. There was nobody behind him at all, but I guess due to lag, my shot ended up connecting with a player that had just spawned, or was otherwise still in spawn and nowhere near the soldier. I still don't get how I actually hit him, and honestly, the ban was kinda justified. I mean, it was bullshit all the same, but still. If the situation were reversed I'd likely ban me too.
And then finally, I was on a server that was playing all of these custom maps. These maps were pretty high quality, and mostly payload. Very well designed, and yet I managed to get severely lost in one of them. There was like a crashed airplane or something that you spawn in on blue side, and I remember getting lost on it. I made a quick quip that I was lost and needed an adult to guide me back to salvation. After a while I got the hang of the map. Then the next map happened, and I once again got severely lost. This one was basically designed to confuse the fuck out of you, and even had a maze like pyramid thing. Well, I'm kinda getting a tad angry and say something like "Holy shit this map is like a maze" and apparently I was "negative" towards the map maker, who I guess was on the server and heard me "complain" about the map. Ended up getting banned because I was "abusive" and "toxic" and didn't "respect" the admins.
tldr; I got lost on a map, said the map was a maze. Map maker heard me, and banned me.