Paul McCartney's Electric Ukulele

Late into his set performing at the 121212 Concert for Hurricane Sandy relief, Paul McCartney joined in with the remaining members of Nirvana for a loud noise workout. McCartney was equipped with what looked like a cigar box with a guitar neck attached. You could see him fiddling with the volume and tone knobs, too. Paul played the thing with a slide. I think it was an electric ukulele. Seeing as how Paul plays a uke in concert, this is my guess. A very arresting looking instrument, though. Quite similar in appearance to the guitar Bo Diddley used to play.