Good ol' boy

When you hear someone talking about a 'good ol' boy,' it conjures up the image of a guy who lives in a small, rural town, drives an old beat-up pick-up truck with a Confederate flag in the back window (which he sees as a symbol of Southern pride), probably chews tobacco and may or may not have a high school education. They are perceived to be prejudiced and racist. Calling someone this is not a compliment, unless you also happen to be a 'good ol' boy.'

Example:
-I live in New York now, but back home, I knew a lot of good ol' boys.
-Really?

Good luck with that!

'Good luck!' can mean just what it says -- that the person is wishing you well in your endeavor. However, 'Good luck with that,' especially when said with a sarcastic tone, means that the other person doesn't think you're going to be successful at all.

Example:
-I'm gonna go cram for my Philosophy final tomorrow.
-Yeah, good luck with that!