"O Tannenbaum" (German for "O Christmas Tree") is a traditional Christmas carol. Track 23 of the album Arthur's Perfect Christmas, it is one of several such carols performed by D.W., however, D.W. does not sing the songs correctly. She instead sings her own entirely made up lyrics to the tunes of the original songs and in this track Arthur calls her out for it.
O tanning mom, o tanning mom...
Stop! Stop! (The accompanying music ends.) You can't sing anymore Christmas songs, D.W. You don't even sing them right.
Okay by me. I don't even see why people like them anyway. They don't have anything to do with Christmas.