upset the apple cart

US /ʌpˈsɛt ði ˈæpl kɑrt/
UK /ʌpˈsɛt ði ˈæpl kɑrt/
"upset the apple cart" picture
1.

計画を台無しにする, 物事をひっくり返す

to spoil a plan or arrangement

:
He didn't want to upset the apple cart by bringing up his concerns during the meeting.
彼は会議中に懸念を提起して計画を台無しにしたくなかった
Her sudden resignation really upset the apple cart for the whole department.
彼女の突然の辞任は、部署全体の計画を台無しにした