The phrase "most shook up" is commonly used to describe someone who is extremely disturbed or unsettled. However, there are several antonyms that can be used to convey the opposite meaning. Some of these antonyms include calm, composed, tranquil, at ease, and relaxed. These words paint a picture of someone who is in control of their emotions and able to handle any situation with ease. Additionally, terms like placid, peaceful, serene, or unbothered can be used, suggesting that the person is not affected by any potential stress or chaos. Overall, there are many antonyms that can help to balance out the intensity of the phrase "most shook up.