Thunb sucking

A boy had reached the age of four without giving up the habit of sucking his thumb, though his mother had tried everything from bribery to reasoning to painting it with lemon juice to discourage the habit. Finally she tried threats, warning her son that, 'If you don't stop sucking your thumb, your stomach is going to blow up like a balloon.'

Later that day, walking in the park, the mother and son saw a pregnant woman sitting on a bench. The four-year-old looked at her for a minute, then said, 'Uh-oh . . I know what YOU have been doing.'