Dealt with crybabies on the internet?

[WhenAliensAttack]

Have any of you dealt with ( or dealing with now) a person on the internet who throws a temper tantrum when things don't go their way and claims that they are "mature", "tell it like it is", and talk crap about a person when the person in particular they don't care for is not in the chat but, as soon as the person pops up they don't say anything. I think it's ridiculous and annoying. I thought people were suppose to not give into petty crap like that on the internet?

I'm interested in hearing your stories about these ridiculous so called "mature" people you have dealt with in chat rooms or any online community.