From Longman Dictionary of Contemporary Englishat somebody’s expenseat somebody’s expensea) PAY FORif you do something at someone’s expense, they pay for you to do it Her mansion was refurnished at taxpayers’ expense. b) HARM/BE BAD FORif you make jokes at someone’s expense, you laugh about them and make them seem stupid or silly Louis kept making jokes at his wife’s expense. → expense
Examples from the Corpus
at somebody’s expense• Several state senators traveled to Asia at taxpayers' expense.• Louis kept making jokes at his wife's expense. 