How do you even respond to that? I've literally gotten some variation of those responses dozens of times from people who learn I'm studying psychology. I laughed once, "No, that's a psychic!" "I mean are you trying to figure my mind out?" Are there any good or witty answers? If you're not exhibiting obvious abnormal behavior, I'm probably not thinking twice about you. I don't even know if they're trying to be humorous or if they're serious.