The Carson Effect

What do these things have in common? A secretary at a company goes to ask for reimbursement for a cab ride, and is told she has been overpaying into her pension and is given almost 6 months' salary. A guy goes to rob a bank, and is given more than 20 times the amount he was asking for. A boy goes to Tiffany's to buy his mother a birthday present, and is sold a $7000 necklace for $1...