Read a book years ago on avoiding tickets, written by a former NY Highwayman.For that question, I would just smile and say “I’m guessing you’re about to tell me…”
He suggested saying, “I must have done something to get your attention!” Which is unusual, funny, and non-incriminating.
Last time stopped, when asked the question, I replied “For driving like a bonehead?”
The cop burst out laughing. There is nothing explicitly illegal about “driving like a bonehead.”