If you have never heard Straight No Chaser then you need to take the time to find some of their stuff. They are an a cappella group formed in 1996. If I am not mistaken, this is an ongoing group that exists at the Indiana University; however, you can buy the music of the original 10 singers still.
My favorite recording from the group is their Christmas album. This particular song- Twelve Days of Christmas- is my favorite. We did all of these songs when I was in High School and it is just hysterical. Enjoy!