The phrase "have shakes" refers to an involuntary trembling of the body, usually caused by anxiety, fear, or a medical condition. Some antonyms for this phrase could be "relaxed," "stable," "steady," "calm," or "composed," all of which suggest a sense of ease and tranquility. Alternatively, "energized," "animated," "vigorous," "lively," or "peppy" could also serve as antonyms, as they suggest a high level of energy and activity in the body. Ultimately, the choice of antonym will depend on the context and tone of the sentence or conversation in which the phrase is used.