There are plenty of holiday songs which feature lyrics that are a bit backwards, but We Wish You A Merry Christmas isn't one of them.
In fact, it's one of the most tame and innocuous songs ever written, so the only way to make We Wish You A Merry Christmas seem backwards is to actually play it backwards.
So that's just what naicisum Rob Scallon did- he recorded the entire carol in reverse, then played it back in reverse so it sounds similar to the original version- only stranger.
This seems like a perfectly appropriate Christmas carol for a year as messed up as 2016...only Rob recorded this song backwards three years ago. Maybe he saw the 2016 crapstorm coming?
-Via Laughing Squid