Antonyms for "am proper for" include "am unsuitable for," "am inappropriate for," and "am unfit for." These antonyms indicate that something is not suitable or appropriate for a particular purpose or situation. For example, a casual outfit may be unsuitable for a formal event, or a child's toy may be inappropriate for a teenager. It's important to consider the context and intended use of something in determining whether it is proper or not. By understanding the antonyms for "am proper for," we can make better decisions and judgments in choosing the right things for the right situations.