One day a few months ago I noticed my roommate's keychain (filled with mementos, trinkets, other people's housekeys, and inside jokes) and thought how appropriate it was; it was such a reflection of who she is. And so began my secret spying of other people's keychains to see if this was a common phenomenon. I learned two things: a) it's actually rare to see other people's keychains without literally asking to see them and b) results are inconclusive. I'm still going to keep an eye out...
In the meantime, here's my thesis, in collage form: