You've heard the infectious song over and over.
Happy is Pharrell Williams' No. 1 hit.
And on Sunday night, Oprah Winfrey sat down with the singer on Oprah Prime and he talked about how — "boom" — the song exploded when the video arrived last November.
She asked him to take a look at a montage of fan videos from around the world, featuring people dancing and singing along to the upbeat tune. Dakar, Germany, Malawi ...
It reduced the singer to tears. And now the touching clip is trending on Facebook, two days later.