"...My dad, may he rest in peace, taught me many wonderful things. And one of the things he taught me was never ask a guy what you do for a living.
"He said 'If you think about it, when you ask a guy, what do you do you do for a living,' you're saying 'how may I gauge the rest of your utterances.' are you smarter than I am? Are you richer than I am, poorer than I am?'
"So you ask a guy what do you do for a living, it's the same thing as asking a guy, let me know what your politics are before I listen to you so I know whether or not you're part of my herd, in which case I can nod knowingly, or part of the other herd, in which case I can wish you dead."
-- David Mamet