Clean excess fat off the pork loin. Place in the bottom of the slow cooker.
Add garlic salt, salt and pepper on top. Pour the root beer over the entire thing; don't worry about the bubbles.
Cook for 8 hours on low.
When finished, remove the pork from the liquid - either transfer the loin into a very large serving bowl, or drain off the liquid from the crockpot itself.
Take two forks and shred the pork into small pieces, then pour most of the BBQ sauce over the pork and mix well. The amount of sauce is up to you, depending on how messy you want your sandwich!
Before serving, toast the hamburger buns - the slight crunchiness helps the bun hold in all that barbecue