Flasher shows front.
Mooner shows back.
Streaker show all.

Streaking was more of a fad, a way to inject some disruption in an event and generally for no particular reason. Flashing, whether male or female, has a sexual connotation to it as the flasher is usually getting his or her jollies somehow. More often associated with men exposing themselves to unsuspecting women, it can go either way.

Mooning though is most often done as a sign of disrespect, although it can be a humorful disrespect just as telling someone to kiss your ass may either be a friendly joke or fightin' words. Mooning is a bit of the art form as well and has a lexicon of phrases associated with it's performance, such as "Pressed Ham" where the mooner sticks his/her ass against a glass window, generally in a car.

Spaw