1. A person, usually a man, who takes pleasure in exhibiting his private parts to random people in public. A cliché flasher wears a dust-coat, flabs of which he spreads in front of his victim(s).
2. A person who interupts tennis/soccer or any other kind of match by running onto it naked. Flashers do it usually without a particular reason, for the sake of doing this.
Ad.1 While I was going to meet you I came across a flasher, lurking in shrubs. He had nothing to be proud of!
Ad.2 Kournikova was to serve when a flasher burst in and ran with his fingers V-shaped.