The phrase "flip one's lid" means to become very angry or lose control of one's emotions. Some antonyms for this phrase might include "maintain composure," "stay calm," or "keep a level head." These antonyms suggest that instead of exploding with anger, it is possible to remain in control and respond to difficult situations in a thoughtful and measured way. Other antonyms might include "relax," "let it go," or "forgive." These antonyms emphasize the importance of releasing negative emotions and moving on from stressful situations without allowing them to overwhelm us.