hair shirt
noun [ C ] uk/ˈheə ˌʃɜːt/ us/ˈher ˌʃɜ˞ːt/
刚毛衬衣（由毛发制成的衬衣，穿着很不舒服，在过去曾被人穿在身上作为因宗教理由对自己的惩罚）
a shirt made of cloth containing hair that feels unpleasant on the skin and was worn in the past by people who wanted to punish themselves for religious reasons