To be clear, this didn't just come out of thin air or because Stephen Colbert's a giant Tolkien nerd - it's because Emma Stone is playing an elf in her new Netflix miniseries, 'Maniac'.
Stone was on 'Late Night With Stephen Colbert' to help promote the show - and just so happened to bring a dog out with her from a rescue shelter - and the two ended up discussing the fact that Orlando Bloom was complimentary of her elven looks on the show. Bloom, of course, played Legolas in 'Lord Of The Rings' and Colbert, being the Tolkien nerd, cracked off into a spiel about the oldest elven character in Middle-Earth - all of which sailed right over Emma Stone's head like the Eagles of Manwë.
That's a little Tolkien in-joke there. (cough) Here's the video.