I love the old English Hymnal hymns sung in church. But quite recently they went all Happy Clappy and struck up a 'hymn' new to me. The chorus went something like "Thank you Oh my Father, for giving uuuuussss your So-o-o-o-o-n..." It was totally dreadful and didn't even scan, but can I get the blooming thing out of my head? Not on your Nellie!
A much nicer ear worm was Tommy Steel "What a mouth what a mouth what a north and south..." (that was last month, but it cheered me up!)