A man and his bored eight-year-old son were walking through a huge open-plan supermarket. The boy amused himself by
throwing up a small coin and catching it in his teeth.   Inevitably he swallowed it and choked.   No-one knew what to do, to save
his life, until a man in a neat grey suit leaped up from the coffee shop, ran to the boy, and grasped him firmly by the testicles -
the boy convulsed and spat out the coin.    His father was most
grateful and thanked the stranger profusely. 'No-one knew
 what to do' he said, 'how did you know? Are you a Doctor?'     'Goodness me, no' said the stranger, 'I work in the income tax department of the Inland Revenue!'