Whatcha in for?

I was thinking earlier this week, how interesting it is that in all different groups, the basic conversations always start out the same. When your with a group of career minded adults, the first question is usually "What do you do?" When you are with a group of college students the opening question is "What's your major?" and when you are in prison they ask "Whatcha in for?"

Why does it matter? I figured out it really doesn't. I don't really think most people care, it's just a good opening when you meet someone new. It works on me.