there are lots of dreams do you no what any of them mean? e.g a nightmare or a ghost or somthing or going to school naked (my friend once had that)
they say that dreams are your deepest, darkest fears/secrets/desires/fantasies. dreams can mean a lot of things really... like your examples:
a) naked in public: maybe we're trying to hide something. or probably, we're not prepared for something.
b) nightmares: like i said, this interprets your deepest, darkest fear planted on your subconscious.