I had one like that a while back. I’d heard the song on Pandora a few times and liked it, but it was just background music while i was working. The tune was catchy, but I couldn’t remember the lyrics at all. I tried humming it into sound hound and stuff, but to no avail.

Finally my wife was playing Pandora when I came home from work and it was on.

Welcome Home, Son - Radical Face

Back in the late nineties I had the reverse problem. I heard a cover of Bakers Street by the Foo Fighters on an independent radio station. I knew it was from a Japanese version of The Colour and the Shape, but no one had the CD. (Actually it was the UK version of the single My Hero, but either I misheard or the DJ was wrong. No wonder I couldn’t find it.) Then, Napster happened. I’ve still got that song somewhere on an old HDD, in all its 128 Kbps glory