The phrase "keep on toes" means to be alert and ready for anything. Its antonyms, on the other hand, include words that express being unprepared, relaxed, or lethargic. Some of these are unguarded, complacent, unvigilant, careless, inattentive, and indifferent. When we say someone is unguarded, it means they are not keeping a watchful eye or being cautious. Being complacent refers to being satisfied with the present situation and not taking action to improve it. Unvigilant suggests a lack of monitoring and awareness of the surroundings. Careless means neglectful or not paying attention to details, while inattentive means not able to concentrate. Lastly, indifference suggests apathy or lack of concern.