From Longman Dictionary of Contemporary Englishthe done thingthe done thingBritish English old-fashioned informalRULE/REGULATION the way of behaving or doing something that is socially acceptable It is not the done thing for teachers to hit children. → thing
Examples from the Corpus
the done thing• It being, of course, not the done thing to drop your trousers in public.• For the great majority, the industrial co-operative is just not the done thing.• I suppose it was not the done thing for a book of Rambles. 