do yourself a mischief
From Longman Dictionary of Contemporary Englishdo yourself a mischiefdo yourself a mischiefBritish English informalINJURE to injure yourself slightly If you try to lift that box, you’ll do yourself a mischief. → mischiefExamples from the Corpusdo yourself a mischief• My objection to his high heels was that he would do himself a mischief if he had to bale out!