My husband has an endearing/sometimes annoying habit (mostly endearing) of picking a song - usually Christmas or Amazing Grace or Domicile On The Place or Oklahoma - his repertoire is quite limited. He'll sing the line of the song, but put another song's lyrics in instead. So, We Three Kings tune is sung, but the lyrics are Amazing Grace - and he embellishes and adds/subtracts his own language as alternative to the established lyrics.
