It mentions that the first use of "Moose" was Crowley in 6x04: "I don't need you to fight my battles for me, Moose. Get Bent."
And it suddenly occurred to me that we all just ASSUMED Crowley was talking about the large elk type of moose. But, what if Crowley was a secret fan of Archie Comics?!?!
Maybe he was referring to Big Moose:
Ok, probably not likely...but it blew my mind for a second there, because it STILL FITS.