Put the pork butt in a slow cooker fat side up with Root Beer or Dr. Pepper. (1 can for every 3 pounds of pork butt). Put on low and let slow cook overnight for 8 hours.
Drain all but 1 cup of liquid and shred pork with 2 forks. Add in as much BBQ sauce as you prefer or a combination of sauces. I like doing BBQ sauce, Sriracha and honey.
Serve BBQ hot on buns with sauteed onions and peppers if desired.