In a small bowl, mix together brown sugar, paprika, garlic powder, onion powder, salt, and pepper.
Rub the spice mixture all over the pork shoulder.
Place the seasoned pork in your slow cooker.
In another small bowl, whisk together barbecue sauce, apple cider vinegar, and Worcestershire sauce.
Pour the sauce mixture over the pork.
Cover and cook on low for 6-8 hours, or on high for 3-4 hours, until the pork is tender and easily shreds.
Remove the pork from the slow cooker and place it on a cutting board or in a large bowl. Shred the pork using two forks.
Return the shredded pork to the slow cooker and toss with the sauce.
Serve hot on buns, in tacos, or however you prefer.
Notes
For an extra smoky flavor, you can add 1 teaspoon of liquid smoke to the sauce mixture. Adjust cooking time based on your slow cooker and the size of your pork shoulder.