There is occasionally some poster who is just trolling, or posting hateful comments or being rude. Or such a fan of a game, he listens to no reason and makes the game could do no wrong and everyone who doesn't like it is a troll themselves.
On facebook, there is an angry face button. On reddit, you can downvote posts.
I guess there is "LOL", but that one is a good one. It means you made someone laugh or cheered them up, so not a negative. That one is my favorite, so whenever I see a rude person, it feels weird to use it when they didn't make me laugh.
I dunno what it could be called. But on reddit, it tends to improve posts a lot. You can really see the trolls/people who post things that are disliked the most. But most of the time, if you make a good post, you get a like or vote up for it.