busman's holiday
From Longman Dictionary of Contemporary Englishbusman's holidaybus‧man’s hol‧i‧day /ˌbʌsmənz ˈhɒlədi $ -ˈhɑːlədeɪ/ noun [singular] British English HOLIDAYa holiday spent doing the same work as you do in your job – often used humorouslyExamples from the Corpusbusman's holiday• Wycliffe was reminded of a busman's holiday he had spent, not so long ago, across at St Mawes.• This, not surprisingly, was enhanced by miniature benches and wooden walling: a busman's holiday to a craftsman carpenter.