Information on this song was hard to track down, until I found the original spelling was WAH-HOO! or maybe even WAH! HOO!

It was written by Cliff Friend in 1936, and recorded by Bill Boyd's Cowboy Ramblers, the Hoosier Hot Shots, the Rustical Quality String Band, The Red Clay Ramblers, and Riders in the Sky.

I found the sheet music being offered for sale at auction by eBay here.

The Indiana University library also has the sheet music. You can see the catalog entry here.

The lyrics are in the DT under the title WAHOO but, interestingly, the line you quote isn't in it – but I'm fairly sure I've heard a version with that line.