Who dat? [catchphrase origin]

From a Bob Stevens cartoon originally published in Air Force magazine, and seen in his collection There I was…: A flight of fighter aircraft over Europe in WWII. One of the pilots gets on the radio and says, ‘Who dat?’ Other pilots join in.

‘Who dat say “Who dat”?’

‘Who dat say “Who dat say ‘Who dat’”?’

‘Who dat say “Who dat say ‘Who dat say “Who dat”’?”’

The flight leader gets on the radio and says, ‘All right, you guys! Knock it off!’

‘Who dat?’

I just heard a version of this exchange in the movie Affectionately Yours. (I like a little noise when I’m working.)

What is the origin of this comedy routine?

First hit on Google:

I should have googled first, but I suspected I’d just get a bunch of Saints links.

Thread title edited to better indicate subject.

Pure bunkum, I say! The phrase obviously comes to us from Who Dat? Root Beer!