It all depends on the tone used to say it... it could mean: you are very funny or very unusual... or very aggressive...either way, it means the person is special, behaves in a not so common manner. In other cases it could be a negative, but it depends on the tone the person who says it uses.

It basically means that you stand out among everyone else. It means that you are interesting. Basically. Also depends on the context, but that is mainly how it is used.