The phrase "rapping on knuckles" has a negative connotation, meaning to chastise or scold someone. Antonyms for this phrase could include praising, applauding, commending, or congratulating. Instead of rapping someone's knuckles for making a mistake, acknowledging their efforts and successes can be a more positive and motivating approach. Other antonyms might include encouraging, supporting, comforting, or sympathizing with someone. When we choose to use language that is supportive and uplifting, we can create a more positive and encouraging environment that helps people learn, grow, and feel appreciated.