Sources on the Consequences of insulting

I recently encounted a situation where some comic fans in my country gathered up and had a Comic Con and it was worth their effort on making their own costumes. They have spend a lot of their time and dedication to represent their fictional characters. After the event was over I saw certain low minded individuals have used certain pictures of the cosplayers and have insulted them in vrry bad ways (memes and some relate to nudity) and it went viral. Some of those cosplayers were pretty depressed after that and all. And the other organizers and them defended them and now it has gone viral all over the world and everyone else is supporting. This is the scenario I encountered. My question is what are the karmic and other type of consequences of insulting a person's character according to the Pali Canon? Can I have references to them? -Metta