Preparation:
In a large nonreactive bowl, storage container, or Ziploc® bag, mix together the banana ketchup, 7UP, lemon juice, soy sauce, vinegar, brown sugar, and garlic until the sugar has dissolved. Add the chicken pieces and toss. Cover the bowl or container or seal the bag and marinate in the refrigerator for at least 1 hour, preferably overnight. When you are ready to cook the meat, heat a grill pan over high heat or heat a charcoal or gas grill to medium.
Reserving the marinade, thread 3 or 4 pieces of chicken onto each skewer, letting the pieces touch slightly, and set them on a plate or baking sheet.
Pour the marinade into a saucepan and bring it to a simmer over medium-high heat. Reduce the heat to medium and cook for 10 minutes; set it aside.
Spray the pan or grill grate lightly with cooking spray. Place the skewers on the grill pan or grill and cook, turning them and basting them often with the heated marinade, until they are cooked through or until the center of a piece of chicken registers 165 degrees on an instant-read thermometer. This should take between 8 and 15 minutes, depending on your cooking surface.
