Speaking of which, I think one's playlist really does reveal one's true character. When you're listening to music (and I assume you're doing this through the means of an audio-transferral device like earphones) it's more or less a private affair; just you and only you enjoying your music. You'll listen to whatever you like - be it reggae or metal or alt-rock - because it's your private time and you want to listen to what you enjoy listening to, simply because that music defines you. I'm probably over-thinking this shit, but it's nice to write out your thoughts based on what you've observed.
More often than not, I've seen friends who listen to popular music who, in turn, love to hang out with the popular kids. I've had friends who dig punk rock, and as such are one of the more extreme deviants of society, doing what they want just 'cause.
Which then brings me to a chicken-and-egg question, are we choosing our music based on who we are, or are we shaped by our choice of music?
And no, you may not slap me.