You are a loiterer, hanging around on the subway platform. You know perfectly well that this is against the rules, but the rules are pretty stupid. And you have good reason to be here, so they can stuff the rules.
You are a guy with a guitar. You've watched all those pitiful slobs on the platforms over the years, playing their crappy music and getting tons of cash dumped in their guitar cases. You eventually decided that this looks like easy money, so you decided to try it out yourself. So you bought this cheap secondhand guitar, plonked yourself down here about twenty minutes ago, and began to sing. You're starting to get annoyed, though -- none of these cheap-ass tightwads riding the trains today want to give you any money! Bastards...
(You are a terrible singer, and a worse guitar player. Don't let that slow you down, though. You're providing them with a service, and they damned well owe you for it.)
A crappy acoustic guitar (Cheap Guitar) -- A really lousy-looking wooden guitar. Once upon a time, it was merely cheap -- now, it's battered as well. It looks like a six-year-old spent years hitting it against furniture. Actually, the more you look at it, the more plausible that explanation sounds.
A guitar case (Guitar Case) -- A plain black leatherette case, suitable for carrying an acoustic guitar. Slightly padded on the inside, with black furry stuff.
Annoying (Annoying) -- This person is just plain irritating. He or she gets in the face of everyone around, and cares little enough about others that you have to wonder if they're a little sociopathic. But no: it's more just a matter of being a selfish jerk than any real mental illness. This disability should be roleplayed to the hilt.