Trim the thickest fat from the butt, and cut the meat into chunks if needed to fit into your slow cooker. Spray the crock with cooking spray.
Toss the meat with the jerk seasoning. Add to the cooker with the onion, and pour the cola over everything. Add the Worcestershire sauce. Cook on low for 8 hours.
Using a slotted spoon, remove the meat to a cutting board and shred. Discard about half the liquid left in the cooker Return the meat to the slow cooker and add the BBQ sauce. Turn the cooker to high and cook until heated through. Serve with your favorite hot sauce.