Misbehaves is a word used to describe when someone acts inappropriately or breaks rules. There are several synonyms that can be used to convey a similar meaning. Some common alternatives include misbehaving, acting out, behaving badly, breaking the rules, causing trouble, disobeying, offending, acting up, and being unruly. While each of these words has slightly different connotations, they all suggest that someone is not behaving in an acceptable or expected way. By using these synonyms, you can add variety to your writing and choose the word that best captures the nuances of the behavior you're describing.