On last night's TONIGHT SHOW, airing from Los Angeles, Neil Young sang his classic song 'Old Man' alongside Neil Young, er, Jimmy Fallon. Check out the performance below!

Ariana Grande did the most during her appearance Tuesday on The Tonight Show Starring Jimmy Fallon. With both her and Cher on the show, Ari then joked of the Dec. 20 installment, "This is one of the ...