Preheat a grill over high heat. Toss the popcorn kernels with the vegetable oil in a large ovenproof skillet. Cover tightly with nonstick aluminum foil, forming a dome, and place on the grill. Shake the skillet, using oven mitts to shield your hands from the grill and hot handle, until the popping starts and then slows down, about 7 minutes. (The corn will start popping after 4 to 5 minutes.) Open the foil, being careful of steam, and pour into a large bowl. Toss with the pepper sauce, butter, Parmesan and salt to taste. Serve immediately.