肉袒负荆　

◎ 肉袒负荆 ròutǎn-fùjīng

[strip off the upper garment as a token of sincere apology——ready to submit to any punishment the other party may want to give] 赤裸上身,背着荆条请罪,表示愿受责罚

廉颇闻之,肉袒负荆,因宾客至 蔺相如门谢罪。——《史记·廉颇蔺相如列传》