When someone is smiling, i want to be mean. what's wrong with me?

Odd isn't it?: There are many words in the english language for things like you describe; contrarians, perverse, oppositional .... To name some. What are your thoughts when you feel this way? When someone smiles what are they talking about? I'm sure those around you probably pick up on some of that. Have you asked if they do sense something? Try to solve it before it harms relationships and your own happiness.

Smiling?: I don't know what the person's smiling means to you, but you're saying it triggers you to want to be "mean." what kind of mean? Sarcastic comments? Physical attack? Do you feel their smiling is directed at you in a negative way, somehow? It may help you to discuss these responses with a therapist -- maybe then you can discover the answer to your question.