Probably claiming the islands.
Best insults you've received in a message

I had some one cuss me out for beating them.
... So i reported him. He didn't get muted or banned and reported me back and i got a 3 day mute.
CLASSIC chess.com! 🙄

cant reach 600 at rapid???? how can u NOT reach 600 in rapid/??? it takes effort to be that bad at chess.
suffice to say its easier to become a grandmaster than to not be able to reach 600 rating at chess
especially given that
600 is the starting rating
so either you basically opened a golf book when you thought it was achess manual
or you are actually referring to cheese, not chess

This was on a forum where someone was complaining about their rating and someone said this. I was 500 at the time

Here's one I received after beating them, but I would hardly call it a good insult
"LOL sad loser with no life cheating in chess.com LMAOOOOOO"

The whole conversation was hilarious, he ended by saying, "Just gona block u since ur stalkng and harasng me"

"Go to Auschwitz" by @KingCatcher91
The most insulting part is that nothing has been done about it so far.

"I've had a couple recently.
"you're lucky, your chess is trash no wonder you're rated 200" meanwhile they lost(600) rated blitz. i dont normally play blitz.
also got called "putin lover" by someone wanting to chat politics during a chess game. seems like a weird time to speak on the state of the world. I'm here to play a game!"
"I'm here to play a game!" -- So is Putin!
I know what the Falklands are and the history thereof. I just don't know what the comment was supposed to mean.
Gloating about the war? Argentina lost that one!