What is not possible?

     It is impossible for a number to be greater than 2 if it is not greater than 1.  It is impossible to find a rational number whose square is 2.   Up to now it has not been possible to show that π is a normal number.  Mathematicians like the challenge of the impossible.  To challenge, to prove, to refute.
     In the poem below Chelsea Martin devises an entertaining web of circular reasoning to explore the impossibility of eating at MacDonald's.

McDonalds Is Impossible       by Chelsea Martin

Eating food from McDonald's is mathematically impossible.
Because before you can eat it, you have to order it.
And before you can order it, you have to decide what you want.
And before you can decide what you want, you have to read the menu.
And before you can read the menu, you have to be in front of the menu.
And before you can be in front of the menu, you have to wait in line.
And before you can wait in line, you have to drive to the restaurant.
And before you can drive to the restaurant, you have to get in your car.
And before you can get in your car, you have to put clothes on.