https://www.youtube.com/watch?v=I4HRbkTx8n4
"Art for Art's Sake", by the Bobs, is not the only a-cappella song that will appear in my favorite songs countdown -- if I'm not overlooking any, there'll be five all told, plus most of a sixth -- but it's the one where I think the fact that no one's playing any instruments is most remarkable. It's why I've linked a live performance by the quartet: I consider it well worth watching. Because it's a New Wave pop song: the first thing we hear is the bassline (sung by the guy with the glasses), and later the chorus is helped into immortality by the glossy synthesizer hook (or that's what Foreigner or Night Ranger or Loverboy would've made it, and you can hear it that way in your head with no effort, although in fact it's sung by the same guy). The guitar solos are sung by the guy with the mustache; they're rather hair-metaly, but brief, and decidedly more fun for their unusual format.