...we can legally play Christmas music.
Anyway, the Men's chorale sang this at my school's Christmas concert a couple years ago. It wasn't on the program, which was the best part haha. The director sat down after they finished their last song and were supposed to leave, but then one of the students ran down and started off this piece. We're singing it again this year, only it will be on the program this time.
We got the song from a group called "Straight No Chaser" who is from Indiana University, I believe. They were the first to do it. You'll see that they do it a bit differently, including an a capella rendition (with the lyrics changed to suit Christmas) of Africa by Toto.
...annnnnnd just because Africa is such a great 80s song, and because I know you're not sick of listening to choir music, here is a mixed choir rendition of it. They create this rainstorm effect by snapping their fingers and hitting their legs and finally the thunder by jumping on their risers. It's a bit cheesy, but if you can get over the cheese factor it's actually pretty cool. I'm not convinced that the thunder sound is completely from the risers, though...