Sicko is a slang term that refers to someone who is regarded as strange, disturbing, or perverted in their behavior. This word has negative connotations, and it is often used in a derogatory manner. However, there are several synonyms that can be used instead of sicko, which are more neutral and less offensive. These include words such as eccentric, oddball, weirdo, kook, quirk, and peculiar. Although these words also describe someone who is outside of social norms, they do not carry the same negative connotations as sicko. Therefore, when describing someone's behavior, it is important to choose your words wisely and avoid using derogatory terms.