A penguin walks into a shop and asks the assistant: ‘Do you have any grapes?’ ‘No,’ he replies.
The same thing happens the next day, and the day after. On the third day the assistant replies: ‘No, and if you come in asking for grapes again I will nail your flippers to the floor!’
The next day the penguin walks in and asks: ‘Got any nails? ‘No,’ replies the assistant. ‘Got any grapes?’ the penguin asks. BOOM!!!