"A traditional custom or idea adhered to although shown to be unreasonable", Mid 16th century: erroneously for Latin sumpsimus in quod in ore sumpsimus 'which we have taken into the mouth' (from the Eucharist), in allusion to the story of an illiterate priest who, when corrected for reading quod in ore mumpsimus, replied ‘I will not change my old mumpsimus for your new sumpsimus’.[mumpsimus etymology, mumpsimus origin, 英语词源]