Exhibitionism, known variously as flashing, apodysophilia and Lady Godiva syndrome, is the psychological need and pattern of behavior to exhibit naked parts of the body to another person with a tendency toward an extravagant, usually at least partially sexually inspired behavior to captivate the attention of another in an open display of bare "private parts" — i.e., parts of the human body which would otherwise be left covered under clothing in nearly all other cultural circumstances.
Typically, the part(s) of the body exposed when referring to "flashing" are bare female breasts and/or buttocks (source). In theory, however, flashing and exhibitionism can also involve the genitalia or buttocks of either gender. A "male flasher" stands in stark comparison to this definition as the latter usually refers to a male indecently exposing his penis to an unwilling observer.
Usually, flashing is done as a momentary "thrill" to inflate the ego of the flasher while having the "added bonus" of increasing the sexual arousal of the recipient(s). Exhibitionists who view exhibitionism as a lifestyle as opposed to a rare thrill, however, more carefully select their target audience and make the exposure brief, inconspicuous and apparently unintentional. While all exhibitionism is, whether on the end of the giver or the receiver, ultimately a sexual fetish, many practitioners see it as an art form. Night clubs and goth bars encourage mild exhibitionism to enhance the venue's atmosphere. This all contrasts with non-sexualized social nudity, in which the exposure is not connected with sexual expression, such as sunbathing or swimming at nude beaches or other participation in public nudity events where nudity is the norm.
Some exhibitionists wish to display themselves sexually to other people singly or in groups. This can be done consensually as part of swinging or group sex. When done nonthreateningly, the intent is usually to surprise and/or sexually arouse the viewer, giving the exhibitionist an ego rush. Some people like to expose themselves in front of large crowds, typically at sporting events; see streaking. A similar phenomenon is when, at the conclusion of a sporting event, a woman may flash her breasts while sitting atop someone's shoulders in a dense crowd of people. Other exhibitionists like to go beyond physical exposure and use the internet to distribute their stories and pictures on websites, sometimes using webcam feeds and other amateur methods. A further purpose here could be to further sexually arouse the recipient by giving the impression that the exposure is "first time" and/or "innocent."