Add the brisket, spice packet, Guinness, and half of the BBQ sauce packet to crockpot and cook on high for 5 hours. (Reserve the other half of the BBQ sauce for later.)
Once corned beef is fork-tender, keep in crockpot on warm for 30 minutes.
Remove from crockpot and cut into cubes.
Preheat nonstick sauté pan over medium heat.
Add corned beef, 1 cup of liquid from crockpot, and remaining BBQ sauce.
Simmer until liquid is nearly gone. Serve with your fave BBQ fixings.