Teetotaler joke

A policeman stops a car and suggests an apparently drunken fellow to take a breath test. He blows, the thing shows: positive. He protests, cries he is a teetotaler and that the instrument isn't working properly. He says his wife is also a teetotaler. She blows- again positive. Then he gives it to their little kid on the backseat- also positive! The ashamed policeman lets them go. They take off and the man says to his wife: - And you kept telling me: don't give the kid any alcohol, don't give the kid any alcohol!