To make the marinade, combine the Barbecue Sauce (1/4 cup), Apple Cider Vinegar (1/2 cup), Cayenne Hot Sauce (1 teaspoon), and Butter (2 tablespoon) in a small pot.
Lightly season both sides of the Chicken Thigh (8) with Salt and Pepper (to taste).
Preheat grill to 350 degrees F (175 degrees C). Grill the chicken 5 minutes on one side, brushing liberally with the BBQ marinade every few minutes.
Flip the chicken over onto the other side and cook for another 5 minutes. This will help initially sear the chicken and crisp up the skin.
Reduce temperature to 250-300 degrees F (120-150 degrees C). Continue to cook chicken and brush with the marinade until the chicken reaches an internal temperature of 165 degrees F (74 degrees C), about 20 more minutes.