Heat oven to 300° F. Spray with the cooking spray or butter a rimmed baking sheet .
Heat the oil in a large saucepan over medium-high heat. Add the popcorn kernels, cover, and cook, shaking the saucepan constantly once the kernels begin to pop, until there is a 2- to 3-second interval between pops, about 5 to 7 minutes. Transfer to a large bowl.
In a medium saucepan, combine the butter, sugar, corn syrup and BBQ sauce. Cook over medium heat, stirring frequently, Keep at a rolling boil for 3-5 minutes. Stir in the salt and pepper. Pour over the cooked popcorn and, with a rubber spatula, toss to coat.
Spread the popcorn mixture on the prepared baking sheet and bake, tossing once, until deep amber, 30 to 35 minutes. Remove from oven, toss, and let cool on the baking sheet. (The popcorn will crisp as it cools.)