barbershop music... hmm like the music they play in barbershops..? If you like that, then I like elevator music.
Actually it originated in barber shops, very long ago. Or, at least, so it's told.
If you don't happen to know what kind of music it is, I'll tell you and I'll give you a link to a video on youtube.
In a nutshell, it's male-only quartets singing popular songs a capella in close harmony. Like this:
OC Times, 2006 International Semi-Final Round