In the restaurant, the waiter said, “We have everything on the menu today, ma’am.”

“So I see,” said the customer.  “May I have a clean one, please?”

What's So Funny?

There are two meanings to the waiter's statement.  He meant, everything that is listed on the menu is available today.  The customer saw many bits of food stuck on the menu and had a different understanding, namely, that every kind of food was making her menu dirty, so she requested a cleaner menu.