As if waiting for a Double-Double wasn’t stressful enough. An Arizona In-N-Out Burger turned into an unexpected fight club after a physical altercation broke out inside the fast food location, with video capturing one man being knocked to the floor by a single punch as customers scrambled to get out of the way. The confrontation reportedly happened while heavy monsoon rains drove people indoors, packing the restaurant with customers trying to escape the storm. A…