A: I built the slaves a church to hang out in on Sundays, even though I didn't have to.
B: Well, that's mighty white of you.
In Harlem in 2010:
A: I'm feeling so generous, I'm gonna eat my food right next to you so you can enjoy the smell.
B: Well God damn, that's mighty white of you - How could I ever repay you for such a selfless act?
Roger: Wow, thats mighty white of you.