Arcade Fire performed "Little Drummer Boy" on Between Two Ferns. Kind of.
The episode featured an awkward, pun-filled exchange between Zach Galifianakis, Samuel L. Jackson, and Tobey Maguire, followed by Arcade Fire's best song ever. "Little Drummer Boy" was awkward, intentionally off-key, and hilarious. Perhaps uncomfortable meta-humor isn't for everyone, but fans of Zach Galifianakis are sure to enjoy this. Or not. Watch it for yourself to find out. The song starts at 3:25 and Win Butler lights a cigarette shortly thereafter.
Source: Funny or Die