Would Upset the Apple Cart?

Spoil carefully laid plans, as in Now don't upset the applecart by revealing where we're going. This expression started out as upset the cart, used since Roman times to mean “spoil everything.” The precise idiom dates from the late 1700s.

How do you use upset the apple cart in a sentence?

You always upset the apple-cart and never agreed with anybody in the class. Matt was so excited about his marriage function, he arranged everything in party so well but the bad weather and heavy rain upset the apple cart.

What does the term apple cart mean?

: a plan, system, situation, or undertaking that may be disrupted or terminated upset the applecart.