Cut as much fat off of the Boston Butt as possible. Place in a 6-quart slow cooker.
Sprinkle the ranch seasoning and Au Jus gravy seasoning over the Boston Butt.
Drizzle the pepperoncini juice over the pork butt.
Scatter the pepperoncini peppers around the pork butt. And scatter the butter on top.
Cover and cook on LOW for 9 hours.
Skim any fat off the surface and shred the meat. Remove any areas of fat as you shred the meat.
Notes
You can use either a bone-in or boneless pork butt. The cooking time is about the same. If you use one with a bone, the bone can be easily removed at the end of the cooking time.