The phrase "where hat I" does not make grammatical sense, and therefore, it is impossible to find antonyms for it. However, if we assume that the intended phrase was "where is my hat," we can identify some antonyms for the word "hat" such as "bald" or "unadorned" if we think about its opposite in terms of headwear. Additionally, if we consider "where is" as a phrase, we can identify some antonyms for the word "is" such as "isn't," "wasn't," or "is never" when we think about negating or reversing the verb. It is important to use correct grammar and language to express clear and precise ideas.