The phrase "on toes" typically refers to being alert or prepared for something. The antonyms for this phrase would be "off guard" or "unprepared." If someone is "off guard," they are not expecting anything and therefore not ready to respond. Similarly, if they are "unprepared," they have not taken the necessary precautions to deal with a situation. Other antonyms could include "relaxed" or "unconcerned," which would suggest a lack of urgency or attention. It is important to stay "on toes" in certain situations, such as in a dangerous environment or during a critical moment, to ensure safety and success.