I got the original recipe from a sample AllRecipes magazine...but of course, I had to 'tweek' it...it turned out pretty tasty.
I'm providing the original recipe with my 'tweeks' in (). Enjoy!

1 (2 lb) pork tenderloin (I used a 4.5 lb pork sirloin roast-trimmed of visible fat)
1 (12 oz) can/bottle root beer (I used 2 cans-store brand)
1 (18 oz) bottle bbq sauce-your choice (I used roughly 1 1/2 Kraft honey hickory smoke bbq sauce-that's all I had on hand. lol)
(I also sprinkled salt and pepper on meat, added a few shakes liquid smoke, and a pinch of dry minced garlic)

1. Place the pork in a prepared slow cooker; pour the root beer over the meat.
2. Cover and cook on low until well cooked and shreds easily-6-7 hours.
3. Drain well. Stir in bbq sauce. Serve over hamburger buns.

**I followed step 1 and 2.
I drained, then shredded the meat, and placed it back in the crock pot.
I added my bbq sauce to the shredded meat then let cook on low for another hour or two. I served it on the buns topped with slaw.

Next time, thinking about using ginger ale...I'm betting it'll be even better.

If the ingredients are bought while on sale, this meal ends up being very inexpensive.
(I bought two pork sirloin roasts on sale for .99/lb. (Froze 1 for later) Total for both was $8.95. BBQ sauce was bought a bit back on sale and with cpns for total of .50/bottle.
Buns was on sale for .99/8pk.
Recipe makes enough for at least 2 meals or 1 HUGE one.