This came from a friend and it made me laugh.
She visited the zoo with her little son and his granddad.
When they reached the penguins the tiny boy poked his finger through the fence and said ‘Duck’
‘No,’ explained Granddad, ‘It’s a penguin.’
‘Duck insisted the little boy.’
‘No. Penguin.’
The tiny child looked accusingly at his grandfather and patiently explained ‘Finger, duck!’