What does naughty mean when..?

Either it means that he likes you, or he is just playing. But it doesn't mean that he doesn't like you. So, there's no worries.

It doesn't mean a thing. It could be a simple sign of flirting, or it could be a sign of "WOW, he just learned a new word". At that age, guys are after only one thing, and that is to get laid. And girls, as they always are, are after getting a boyfriend who likes them, treats them well, loves them the most, spoils them, cuddles them..... You get the point.. Just be careful who you are dealing with and see what they really want before you get yourself into a mess, because most times, you don't realize it only after it is too late and you are neck deep covered in drama. That'd be really Nasty. (Not naughty but close)

It may mean something along "sexual Naughty" but that's my opinion.

That all depends on what you are doing and how you want it to mean.....being that you are not yet 18 I would say that any guy calling you "bad" or "naughty", is not a guy you want to know.

It really doesn't mean that much of anything he is basically just saying that he's noticing you and flirting.