Use the word "naughty" to describe bad behavior, especially when describing children. Naughty behavior is not extremely bad, but it’s bad enough to draw the attention of parents or other adults who witness it.
Those children are being naughty.
The girl was punished for being naughty.
A boy was sent to the school’s principal because he used some naughty words in class.
Santa always knows which children are naughty or nice.
The movie we saw last night had a few naughty parts.
Las Vegas has a reputation for naughtiness. (The word "naughtiness" is a noun.)
Bobby is usually a good boy, but sometimes he’s naughty.