I've been in New Orleans for less than 24 hours and I received my first "who dat?"
I was running down St. Peter near Royal Street and some random guy cleaning in front of an establishment of questionable morals (the establishment not the guy. not judging, though), said "Yo, who dat, man?" I returned proudly with, "me dat!"
And I speak for a living....... Oh well, I have the rest of the day.