Usually a single curse word or indecency during a live TV or radio broadcast. It's the media's version of the "F-Bomb", used by the FCC in assessing fines against broadcasters.
Joe Biden's comment on Health Care Reform after introducing the President ("...it's fucking important...") was a Fleeting Expletive.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.