coffee

So I'm at the hardware store and I see this guy walking across the parking lot very slowly balancing a small coffee cup on the palm of his hand. He's being very careful not to spill. We are both walking toward the door and I can see that we will probably arrive at the same time. So I slow down to let him go first. As he nears the door I intentionally take a step back. He is still balancing the cup. He very carefully opens the door with his left hand while balancing his coffee on his right palm. He successfully opens the door and starts to walk through. The door swings back and hits his hand which knocks the coffee cup to the floor spilling its contents everywhere. He looks at me and says, "You're going to have to clean that up." and walks away.     ?