What are the puns in English?

In the above topic: hi, Jack means: hijacking, hijacking, because hijacking is a word pronounced the same as hi, jack, so there is a joke that jack is the most unpopular person on the plane, because if you say hi, jack, passengers may lie down because they think someone is going to hijack.

Other examples are:

1) Don't ask for trouble.

2) I have never seen a saw saw.

3) If cans can be filled, can cans be filled with cans?

Of course, the coolest example is KFC's slogan:

We are right to cook chicken.