You might remember the Mathematical Love Song by the Klein Four Group. From the same performance, here’s their imaginative arrangement of The 12 Days of Christmas. -via Educational CyberPlayground
I've seen Straight No Chaser sing it in concert and it's on their CD. Don't know if they originated it or not but it's great and a longer version than the one posted ablove. http://www.youtube.com/watch?v=2Fe11OlMiz8
I'm so happy to see this on Neatorama! The guy on the right was my vector calculus teacher, and even though I got a C in the class, it was a joy to see how excited he was every day to teach such an exhausting class. You can buy all of The Klein Four's songs on iTunes!
http://www.amazon.com/BOCA-Humor-Wasting-Parents-Money/dp/B00003G1RR
Although, I admit the I dont know if they got it from somewhere else, too.