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

1.
由某人承担费用, 以某人为代价
paid for by someone; causing loss or damage to someone
:
•
The company party was held at the company's expense.
公司派对是由公司出资举办的。
•
He made a joke at her expense, which made her feel uncomfortable.
他拿她开玩笑,让她感到不舒服。