Deliberately refusing to answer someone's question and/or potentially confusing them under the pretext of joking around is no way to behave regardless of whether or not you're on the internet and regardless of whether or not they're a troll. Chances are you wouldn't do it in real life so what makes you think it's okay to do on the internet? If you're going to do stuff like this then don't get bent out of shape when someone calls you out on it and tells you to stop.