Act the giddy goat
Act the giddy goat : Phrases
The phrase 'act the giddy goat' (or 'play the giddy goat') wasn't coined from scratch but was built up by degrees from earlier phrases. 'Giddy' has been used to mean foolish or stupid since the First Millennium and has been applied as an adjective to all sorts of creatures and prominent amongst these was the ox. There are several citations of 'play (or act) the giddy ox' which pre-date the 'giddy goat' variant. For example, the British comic Ally Sloper's Half-Holiday used the phrase in a March 1892 edition:
"Fanny Robinson was flighty; she played the giddy ox - I mean, heifer."
We also find 'acting the goat' from 1879, when H. Hartigan included it in his memoir Stray Leaves from a Military Man's Note Book:
"Don't be actin' the goat."
Given 'acting the goat' and playing the giddy goat', it isn't much of a jump to 'acting the giddy goat'. This is the 'giddy' phrase that has lasted, possibly because of the alliteration. Also, the behaviour of goats can well be called giddy; they are certainly capricious - capra is the Latin for goat.
The first mention of it that I can find in print is from a US source, in a story about a literally giddy, i.e. drunk, goat, in The Mountain Democrat, February 1896:
Then Nanny drank her tot like a man. It was too absurd to watch her conduct after this. She would skylark with any one, charge up and down the deck, butt anybody who came in her way and, in fact, play the "giddy goat".
The quotation marks in that citation suggest that the phrase was in use by 1896 and we may expect earlier citations to show up at some point.