"Cop some zs" is an informal expression used to indicate going to sleep. While it has no proper antonym, other phrases can be used to describe staying awake or resisting sleep. Some antonyms might be "stay up," "remain alert," or "resist nodding off." Although these phrases express the opposite of "cop some zs," they don't share its connotation of restfulness, and staying awake might be difficult or uncomfortable. People who avoid sleeping can be described as "insomniacs," "night owls," or "chronic insomniacs," depending on the cause of their sleeplessness. Ultimately, the antonym of "cop some zs" must be determined by the context in which it is used.