"Hitting up" is a colloquial phrase that typically refers to socializing or engaging someone in conversation. To find antonyms for this phrase, one can consider words that signify the opposite of socializing or conversing. Some possible antonyms could include avoiding, ignoring, shunning, snubbing, or isolating. These words suggest a deliberate effort to distance oneself from others or to refrain from engaging in social interaction. Alternatively, one could consider words that suggest a lack of enthusiasm or interest in the conversation, such as disinterested, listless, indifferent, or apathetic. Overall, antonyms for "hitting up" convey the opposite sentiment of sociability and may indicate a preference for solitude or disengagement.