OK, maybe not strictly musical (though a character was playing blues on a Gibson Hummingbird!) but someone in this US novel I was reading was described as having a Gimmee cap (which I guess is a baseball cap given away free with an advertising slogan or logo on it?) and others wore Stetsons with "cowboy crease" and "Canadian crease". What's the difference?
...and do Americans really say "copacetic" for OK? My dictionary says "origin unknown". Any ideas where it comes from?

RtS