An Irishman took a photograph

An Irishman took a photograph of his son to the chemist. 'I wonder,' he said, 'could you enlarge this for me?' 'Yes, certainly,' the chemist replied. 'And would it be possible for you to take his hat off for me?' 'Well, I'm sure we could do something. Yes, we could touch it up for you.' 'Oh, that's fine.' 'Tell me,' said the chemist, 'which side does your son part his hair?' The Irishman smiled. 'Oh, come on now. You'll see that when you take his hat off.'