A moth comes into a chiropodist's.
'Can you help me, please?' the moth asks. 'I'm desperate. My wife has left me. My business has gone downhill. My daughter's on the game. I'm in complete despair. You've got to help me.'
'But how can I help you?' said the chiropodist. 'What you need is a psychiatrist. Why did you come and see me?'
'The light was on,' said the moth.