I sometimes will answer with a silly reply, like was alluded to before. Like "I study herring communication", or something like that. It usually gets a little laugh, especially if I go into details about how they communicate and usually people let me just leave it with that. It's really a win-win. It allows for a non-awkward conversation, maybe funny and a little silly, breaks the ice, and you don't have to lie (usually they know you aren't serious) or reveal anything you don't want to.