Don't explain, it shatters the illusion. You should cultivate an air of mystery. This is how Ged gets all these loose women - it's not just his Nissan Primera, it's the valves, he doesn't explain them. You ask him what he does, and he just says, "valves," mysteriously. Well, have you got a scooby about them? Even after interrogating him at length?
Mystery, trust me mate. Have I ever dispensed duff advice?