upset意思是「使心煩、顛覆、擾亂」，apple意思是「蘋果」，cart意思是「二輪貨運馬車」，upset the apple cart意思是「推翻運蘋果的手推車」，引申指「搞亂（某人的）計劃、破壞任務。比如It upset the apple cart.打亂計劃。
看看老外聊天時怎麼用upset the apple cart：
A I am planning to give a surprise to Maggie and ask her to marry me tonight.Can you help me？
B I am willing to help you，but I might upset the apple cart
A 我打算今天晚上要給瑪吉一個驚喜，然後跟她求婚。你可以幫我嗎？
B我是很願意幫你，但是我有可能會打亂你的計劃。
upset the apple cart例句精選：
Tom really upset the apple cart by telling Mary the truth about jane.
湯姆把珍妮的真實情況告訴了瑪麗，他可真把事情給搞砸了。
Don't try to deal with important issues or make changes that will upset the apple cart.
儘量不要處理重要事務，也不要做出破壞別人計劃的改變。
We sell quality, validating relationships that protect your core relationship, he says. We want people who are not going to upset the apple cart.
我們出售高品質、有實效的兩性關係，同時保護你的核心婚姻關係，他說，我們需要不會擾亂家庭秩序的人。
It is best not to upset the apple cart if you learn information that may damage a colleague's reputation.
如果獲得了可以損壞同事名譽的信息，最好不要洩露出去。
One of the worst things someone can do is "upset the apple cart" by deviating from the plan.
一個人所能做的最糟糕的事情，就是偏離這項計劃。