Antonyms for the phrase "returning compliment" include criticism, insult, and offense. While returning a compliment is a socially accepted norm, criticism is more often considered to be negative and confrontational. Insults are often intended to cause harm or hurt someone's feelings, while offense is more about causing someone to feel negatively about a situation or comment. In general, the opposite of returning a compliment is to respond in a negative or critical way, which can result in interpersonal conflict or a breakdown of communication. It is important to use language carefully to avoid misunderstandings and hurtful exchanges.