DrFrasierCra

Pretty sure it's like this:

Oh when the Saints first came to town
When the Great MacNutt and Morgus was around
When interest rates just had one number
That's when that Who Dat fever came to town.

Who could forget Old Archie Who
And Who Dat kicked twice as far with half his shoe
And Willow Street could not believe the numbers
That came to scream and shout and whoop.

"The Great MacNutt" and "Morgus" refer to some original TV programming from WWL and WDSU from as far back as the late 40s.

Interest rates having "one number": when the song was originally written in 1983 (at the time Bum Phillips was at the helm - the version you reference here was actually the second version of this song), mortgage rates were over 10%, but in the 60's (when the Saints franchise began), they had been lower, i.e. in the single digits.

As for Willow Street - the Saints, of course, played at Tulane Stadium before there was a Superdome, and Willow Street was considered the "front" of the stadium (the way Poydras is considered the "front" of the Superdome today).