I inherited my grandmother's music collection when she died a while back. One of the songs I liked was Sleepy Time Gal. The version of the song on Youtube is rather slow; Grandma had a dance version of the song which is faster and more interesting.
So I've had this song memorized for a while. Imagine my shock when I learned that the song has lyrics. Now I feel compelled to memorize the lyrics, simply because I know the tune.
I also feel compelled to go through all her other songs, and see if they have lyrics, too. What about the polka for I Never Promised You a Rose Garden, or the trumpet rendition Make the World Go Away? Those titles sound like they would be for songs with lyrics.
Does that ever happen to you, readers? Do you memorize a tune, without knowing that it has official lyrics? Or do they tend not to make instrumental versions of songs anymore? I don't think I ever hear instrumentals on the radio, certainly not instrumental versions of Sleepy Time Gal.