Green’s Dictionary of Slang

giddy gout n.

also giddy
[rhy. sl.; note popular juv. rhyme ‘Giddy, giddy gout, your shirt is hanging out!’]

(Aus.) a boy scout.

[Aus](con. WWI) A.G. Pretty Gloss. of Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: giddy. A boy scout; abbreviation of ‘giddy gout.’.
[Aus]Pete’s Aussie Sl. Home Page 🌐 giddy gout: a boy scout.