Robert Baden Powell himself posted this on YouTube, so it must be an official Scout song:

https://www.youtube.com/watch?v=ZmpPUEqweRA

The song is in The Gilwell Camp Fire Book and The Australian Boy Scouts Song Book. Didn't find it in any Girl Scout/Guide songbooks. I always thought the song was obnoxious, but then I thought that about a number of songs my sister sang....