On The Rocks are the University of Oregon's acapella men's choir and they are great entertainment.
They are very funny, hugely entertaining and, best of all, talented singers. To watch an amateur recording with poor quality sound of Bad Romance, the Lady Gaga song, listen here. I think is the best thing they do. I watch it any time I need cheering up!
9th April 2011update. This post now links to an alternative but not-as-good-but-still-OK version because the original was removed by YouTube for a 'violation of user terms' after nearly seven million (yes, 7,000,000) hits!