“To upset the apple cart” means to create a difficulty or spoil carefully laid plans.
This phrase is first recorded by Jeremy Belknap in The History of New Hampshire, 1788:
“Adams had almost overset the apple-cart by intruding an amendment of his own fabrication on the morning of the day of ratification” [of the Constitution].
In the 1800s “apple cart” was wrestlers’ slang for the body and “down with his apple cart” meant to throw a man down.
One theory as to the origin says the Romans had a similar expression “Perii, plaustrum perculi” — “I am undone, I have upset my cart.”
A more basic, common sense theory suggests that it generally refers to farmers in the 1800s, would bring to town apple carts loaded with neatly piled, fresh apples for sale. A clumsy person would come along and knock over the cart, spilling all the apples.
The etymologist Walter Skeat wrote in 1879, “I think the expression is purely jocular, as in the case of ‘bread-basket,’ similarly used to express the body.”
An example of the phrase’s use appeared in The Champion and Weekly Herald (London), 16 Apr. 1837. “The Whigs, Gentlemen, cannot object to the soundness of our old authorities in law, because, you know, they themselves are very fond of referring to the same source, when it suits their purposes; and to deny those authorities, therefore, would be at once to upset their own apple cart.”
Another appears in Notes and Queries, 13 Dec. 1879. “If a child falls down you first inquire if he is much hurt. If he is merely a little frightened, you say, “Well, never mind, then; you’ve only upset your apple-cart and spilt all the gooseberries.” The child perhaps laughs at the venerable joke, and all is well again.”
By the early 1900s, the phrase had become widely popular and shifted from slang to colloquial usage. The evidence suggests a peak in the 1930s, possibly helped along by George Bernard Shaw’s play The Apple Cart, first produced in 1929.
The popularity of the expression is probably due to the vivid image of a cart loaded with apples overturning and the resulting mess, inconvenience and financial loss.
Perhaps I could use my favorite fruit and call it “upsetting the raspberry bucket.”