What are some of the funniest puns you have heard in the English language? Go!

Do other languages have this phenomenon we call puns?

If you don't know what a pun is, here is a very corny example:

The duck said to the bartender, "put it on by bill."

It's a pun because 'bill' has 2 meanings. Bill is what you call a ducks nose and bill is also what you can say for the check at a restaurant.

Mine is not very funny, so please share funnier ones below!