Where did the phrase 'trying to get your goat' come from and what does it mean?
I believe the expression 'to get your goat' has it's origins in horse racing.
Race horses are very high-strung animals. Goats are often used as companion animals, to keep a horse calm.
Someone wanting to fix a race would slip into the barn the night before the race, steal the goat, then an upset, distracted horse would run a bad race.
Hence, if you are upset and not at your best, it is said that 'someone has gotten your goat.'
Further, this cliche has been replaced by the modern slang idiom, " push your buttons ", meaning successfully annoying you or even angering you. Not as colourful imagery as the original expression, but much easier to understand for people in a modern technological society.
I disagree. I think this expression comes from the use of a goat as bait for big game hunters. For instance, if the tiger" gets your goat", and you don't bag a tiger, you've got one ticked off hunter on your hands. Most horse people I know keep a donkey as a stablemate for skittish horses.
The racehorse story is correct. It's possible that there are two separate origins for the same term, but in the USA, where there are no tigers, the goat was used as a companion for the high-strung racehorse, and if someone got his goat, the horse would run a bad race. Or it might backfire and the horse runs faster than ever. But that's the American origin of "get your goat," and Brewers Origins of Phrase and Fable classifies this as an "Americanism," so that casts the tiger story into great doubt.
It means to act foolishly. There are many forms of this phrase too such as in 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." Also the phrase "Acting the goat" can mean the same thing like in the memoir Stray Leaves from a Military Man's Note Book: "Don't be actin' the goat."
The phrase "Ride the Goat" is actually based on a misreading of an acronym used by Freemasons. The Supreme Being, having many names in the different religions of the world, is referred to by Masons as the "Great Architect of the Universe", abbreviated G.A.O.T.U. . You can readily see how the word "goat" is derived from this abbreviation.