Saw it on TV once or twice, but of course, youtube.com has them.
It's gotta be one of my favorite commercials because I've been that guy singing and then realize someone is either next to me or in the same room and I get embarrassed.
http://www.youtube.com/watch?v=CiHBqOll7js - Original
http://www.youtube.com/watch?v=VYfw2qLdeFQ - Alternate
http://www.youtube.com/watch?v=5DlVRKNnZtQ - Alternate 2