Young son has swallowed a coin

The frantic-looking lady came rushing out of her house into the street and
cried: ?Help! Help! My young son has swallowed a coin and is choking. I
don?t know what to do!?
Everyone looked the other way, except for a middle-aged gentleman who
rushed into the lady?s house, found her young son, turned him upside down
and shook him until the coin fell out of his mouth.
?Oh, thank you!? cried the lady. ?Are you a doctor??
?No madam,? replied the middle-aged man. ?I?m from the Income Tax