Mathematical Puzzle: IF 23+4...

A man walks into a hamburger shop and orders a regular meal. Later, the waitress brings his meal to him. He takes a bite out of it, and notices there's a small hair in the hamburger. He begins yelling frantically at the waitress, "Waitress, there's a hair in my hamburger! I demand to see what is going on!"
So, the waitress takes him back where the cook is and to his demise, he sees the cook take the meat patty and flatten it under his arm pit. He says, "That's disgusting!"
Then the waitress says, "You think that's disgusting you should see him make donuts."