A policeman stops a car and suggests an apparently drunken fellow to take a breath test.

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!
!