Here's something we missed on Late Night With Jimmy Fallon the night before last. Fallon and guest Joseph Gordon-Levitt, apparently friends in real life, got together to sing karaoke and do impressions of other singers. Fallon, as David Bowie, sang Foster The People's "Pumped Up Kicks." JGL, as Axl Rose, sang Kelly Clarkson's "Since U Been Gone." And then the ...