Place the chicken breasts in the slow cooker.
In a bowl, mix barbecue sauce, vinegar, brown sugar, garlic powder, and red pepper flakes.
Pour the sauce over the chicken, coating evenly.
Cover and cook on low for 4-6 hours or on high for 2-3 hours, until the chicken is tender.
Use two forks to shred the chicken directly in the crockpot.
Stir well to coat the shredded chicken with the sauce.
Let it simmer for an additional 10-15 minutes for extra flavor.
Serve hot on buns, over rice, or with your favorite sides!