Be civil. Don't say things you wouldn't say in a face-to-face conversation. Avoid gratuitous negativity.

When disagreeing, please reply to the argument instead of calling names. E.g. "That is idiotic; 1 + 1 is 2, not 3" can be shortened to "1 + 1 is 2, not 3."

Please don't insinuate that someone hasn't read an article. "Did you even read the article? It mentions that" can be shortened to "The article mentions that."

https://news.ycombinator.com/newsguidelines.html

It's not called "left-coast/euro sensitive", it's called manners.

However, I will put what lorenzhs said a bit more bluntly.

Please don't go out of your way to be a dick - there is no need for it, and it benefits nobody.