He seems so focussed on his own “problem” that he hardly even notices what’s going on right next to him. It’s quite unbelievable.
The man is not the only one walking back to the counter with his burger. Several other customers in the restaurant follow. One is friendlier than the other. This man wonders in amazement why his burger looks so squished. He suspects that something fell on top of the Whopper before it was served.