Do you slouch when you're sitting or keep body posture upright?

I sit straight.  Slouchers annoy me, looking all untidy.  Partly I was brought up that sitting straight is good manners, and despite what certain game sites claim, slouching doesn't make you look "relaxed" like a mafia boss.  A mafia boss is going to exude "I can have you killed" energy no matter how they sit.  I used to fence (the sword kind, not the stolen goods kind) and have very well developed core muscles.  Good posture takes no effort from me.  I'll give you a pointer, it doesn't come from your shoulders, which should be relaxed, but by rolling in your tailbone so that it lines up with the point where your spine enters your skull.  This should push up your trunk from your core whether you sit with your legs crossed, together or apart as it pleases you.