Remove packaging from pork shoulder and pat it dry. Generously rub the shoulder with mustard until evenly coated, then generously rub the shoulder with seasoning (1/4 - 1/2 cups worth)
Using plastic wrap, tightly wrap up the pork shoulder to seal in all the flavors. Refrigerate overnight or up to 24 hours.
Set smoker at 225 degrees. Smoke pork shoulder for 6 hours.
Remove pork from smoker and place (fat side up) in your large crockpot. Cover and cook on high for another 6 hours.
Shred meat, remove fat & bone. (Can reserve bone and a little meat for beans later!) Return meat to crockpot and serve with your favorite BBQ sauce or taco fixings.