iGuitar
Similar to air guitar but with an iPod in one hand, headphones in, the other hand moving like playing a guitar. Because nobody else can hear the music, they look a bit more than stupid.
Person 1: "What the hell is he doing?"
Person 2: "I dunno, he looks a bit daft"
Person 3: "He's iGuitaring!"
Person 2: "I dunno, he looks a bit daft"
Person 3: "He's iGuitaring!"