Breast-beating is a term that describes the act of making a show of one's guilt or remorse. There are various synonyms for this phrase that can be used to convey the same message. One possible synonym is "self-flagellation," which refers to the act of punishing oneself as a way of expressing regret or repentance. Another option is "self-reproach," which means to criticize oneself for one's actions. "Self-chastisement" is another synonym that is commonly used to describe the act of punishing oneself or being overly critical of one's actions. Lastly, "self-condemnation" refers to the act of criticizing or blaming oneself for one's mistakes or shortcomings.