get someone's goat

To annoy or anger one. That guy just gets my goat every time he opens his mouth.

Annoy or anger someone, as in By teasing me about that article I wrote, he's trying to get my goat, but I won't let him . The origin of this expression is disputed. H.L. Mencken held it came from using a goat as a calming influence in a racehorse's stall and removing it just before the race, thereby making the horse nervous. However, there is no firm evidence for this origin. [c. 1900]

If someone or something gets your goat, they annoy you. If there's one thing that gets my goat, it's some fashion critic telling us what we can and can't wear. It was a bad performance, but what really got the media's goat was the manager's refusal to take the blame. Note: This expression may be connected with the early 20th century practice in America of putting goats in the same stable as racehorses, since the goats seemed to have a calming effect. If someone stole the goat, the horse would be upset and its performance would be affected.

To annoy someone, to make a person lose his or her temper. This term is definitely American in origin, but its precise provenance has been lost. H. L. Mencken was told that it came from the practice of putting a goat inside a skittish racehorse’s stall in order to calm it down. Removing the goat shortly before the race would upset the horse and reduce its chances of winning, a ruse supposedly planned by a gambler who had bet on the horse’s losing. This explanation seems more far-fetched than a possible connection of the term with the verb “to goad.” In any event, it came into use about 1900.