This may be the funniest thing I’ve seen all year. It’s Tenacious D singing “You’re The One That I Want” (from Grease) as a duet with Andy Serkis, who sings in voice and character as Smeagol.
Apologies if you’ve seen it already and/or just don’t think it’s very funny. 
Link may or may not be SFW depending on your W. There’s singing and some language.