Ever want to see Joseph Gordon-Levitt kill it in karaoke with a spot-on performance of Axl Rose in "Since You've Been Gone" by Kelly Clarkson? Or see Jimmy Fallon's effort as David Bowie in a Foster the People ditty that makes the sugary pop song strangely... poetic? How about watching the two of them screech out the high notes in Lady GaGa's "Edge of Glory"?
Yep, we knew it, and they did too, apparently, as the "50/50" actor appeared on "Late Night" to promote his newest film and pop out an unforgettable ballad or two.
HuffPost Entertainment is your one-stop shop for celebrity news, hilarious late-night bits, industry and awards coverage and more — sent right to your inbox six days a week. Learn more