I saw this clip yesterday and I was cackling with delight.
Jimmy Fallon does perhaps the best impression of Neil Young I've ever seen -- he nails that folky falsetto just right. Here he has Neil performing Willow Smith's hit song, "Whip My Hair." Halfway through, Neil gets a surprise visitor -- none other than Bruce "The Boss" Springsteen, dressed up in his 1970s "Born to Run" get-up. It's inspired comedy, taking the simple pop song and making it a dark, depressing 70s era folk song.