at someone's expense
US /æt ˈsʌm.wʌnz ɪkˈspɛns/
UK /æt ˈsʌm.wʌnz ɪkˈspɛns/

1.
누구의 비용으로, 누구를 희생시켜
paid for by someone; causing loss or damage to someone
:
•
The company party was held at the company's expense.
회사 파티는 회사 비용으로 열렸다.
•
He made a joke at her expense, which made her feel uncomfortable.
그는 그녀를 희생시켜 농담을 해서 그녀를 불편하게 만들었다.