South Korea’s version of the KFC Double Down—boldly called the “Zinger Double Down King”—has just upped the ante of all meat-only sandwiches. It’s a culinary creation so audaciously meated, even Ron Swanson would shudder at the prospect of consumption. Unlike the timid American version of the deep fried sandwich, that merely puts bacon and cheese between two chicken cutlets, the Zinger straight-up crammed a hamburger into the mix. The 750-calorie creation will only set you back $7, so yeah, it’s totally worth the trip …