Place pork roast in crockpot.
Add large onion, sliced and 2 Tbs. Worcestershire sauce.
Add water to cover.
Crock on low all day (at least 12 hours).
Remove roast, discarding cooking water. Save onions.
Fork-shred pork, discarding any fat and bones.
Return shredded meat and onions to crockpot.
Dump a bottle of your favorite barbeque sauce over it and crock an hour or so on low until heated thoroughly.
Serve on heated buns.