I to am a returned serviceman in Australia I have been asked this question by both children and adults. Children I can understand as they are naturally inquisitive and I just explained that there are some questions that you shouldn't ask and why. With the adults you have probably noticed that they have never served their country, community or they would know that the question is very rude and inappropriate. The only times that I have been asked this by adults has been at my local pub and I just let the person know that it is definitely none of their business and go back to enjoying my beer. just my 2 cents worth.