The tax man and your child

A man walks into a store followed by his ten-year-old son. His son is spinning a quarter in the air and catching it between his teeth. While walking through the store someone bumps into the boy and the coin goes straight into his mouth and lodges in his throat. He immediately starts choking and going blue in the face. His dad starts panicking and shouts and screams for help.
A middle-aged, fairly unnoticeable man in a gray suit is sitting at the snack bar in the store reading his newspaper and sipping a cup of coffee. At the sound of the commotion, he looks up, puts his coffee down, neatly folds his newspaper and places it on the counter. He gets up from his seat and makes his unhurried way towards the boy. When he reaches the boy, the man carefully takes hold of the boy's testicles and squeezes, gently but firmly.
After a few seconds the boy convulses violently and coughs up the quarter, which the man catches in his free hand. Releasing the boy, the man hands the coin to the father and walks back to his seat at the snack bar without saying a word.
As soon as the dad makes sure that his son is OK, he rushes over to the man and starts thanking him saying, "I've never seen anybody do anything like that before. It was fantastic! Are you a doctor?"
"Oh, good Heavens, no," the man replies, "I work for the Internal Revenue Service."