Ugly Christmas sweaters usually don't offend more than the eyes, that is, unless the sweater hasn't been washed in a while then it will offend both the eyes and the nose.
But adding musical elements like bells to an ugly Christmas sweater seems like it would take the tackiness too far and turn the sweater into a weapon, since it could potentially offend three of the five sense at once.
However, after seeing this video Gerry Litwin uploaded to YouTube showing his coworker playing Carol Of The Bells I'm convinced musical ugly sweaters could be used for good after all!
-Via Geekologie