I always thought the clown's body was a big, green, alien's head. Anyone else see it that way? The red bit (which I suppose is the clown's arm) is an eye or visor, and it's looking up at the girl.
That testcard is such an iconic image, very cleverly composed. A couple of slapdash "remixes" for an arcane laugh: http://www.myspace.com/phantomcircuitradio/photos/albums/my-photos/596463