To overtly perform an emotion, state-of-being or sentiment, when one has no direct experience with the thing performed. Inspired by Tom Cruise's appearance on Oprah in May 2005. In telling about his love affair with Katie Holmes, Cruise jumped up and down like a rabid chimpanzee and, quite literally, humped the couch. The act of humping the couch is synonymous with being overly affected. As Cruise surely had no idea what it looks or feels like to be in love, he resorted to air humping near furniture.
Those kids at the Phish concert drive BMWs and live in the suburbs, yet they dress like hippies. All their talk about world peace is just humping the couch if you ask me.