Cook 4-6 frozen chicken breasts in crockpot on high for 4-5 hours, or on low for 6-8 hours. (Make sure to add enough water to crockpot to cover chicken.) (Can add some finely chopped onion if you like that in your BBQ.)
When chicken is done cooking, drain water. Shred chicken with 4 forks. Add BBQ sauce and stir/toss chicken until it is evenly coated. Serve on hamburger buns. Enjoy!