Couric asked, "What is that when you jump around, and carry on, and do the, "Who dat? Who dat?" stuff?
"That's our chant from the fans," Brees said. "We do it just to kinda get the fans hyped up, you know? 'Who dat? Who dat? Who dat say they gonna beat them Saints?'"
Brees and his wife Brittany say it goes back to the culture and the bled of the city. "You could be anywhere in the world, and somebody yells, 'who dat," and everybody from Louisiana's gonna, you know turn around it's 'ok, i gotcha.'"
See the full interview, here.