I'm not a fan of that actor so I tweet mean things at them
Why would you say mean things on the internet?
I just don't like him.
The way you act online reflects your personality. Do you really want others to see you in this kind of light? Even if you're anonymous someone could still find out who you are.
It's just the internet, who cares?
I'm sure the people on the other end of your attacks online care. They don't even get the right to appropriately accuse their harassers. Hiding behind a screen and attacking others is cowardly.