No, their not interested in your actual reply to a question like that.
They're looking at you as you struggle to answer it. Are you amused by the question and smile? Or totally phased and panicked by it? Can you look at them while you think of an answer? Do you give them an equally silly response? Or do you feel you have to turn it into a sensible topic. Do you feel able to ask for help?
A question like this can be a very simple way of getting an insight into your personality type, how you may deal with the unexpected and what you might be like to spend 8 hours with.