In a large skillet, heat oil over medium-high. Add chicken breasts, season with salt and pepper.
Cook until meat is golden brown, 5 mins. With a slotted spoon, transfer to a slow cooker, leaving as much oil behind as possible. Repeat with chicken thighs.
To the skillet, add onion, garlic and bell pepper and cook over medium heat.
Stir constantly, until onion is translucent, 6 mins.
Add 1/4 cup water and cook, stirring and scraping up browned bits from skillet for about 5 mins. Season with salt and pepper.
Transfer to slow cooker.
To the slow cooker, add tomatoes, hot pepper sauce, Worcestershire, mustard, and brown sugar. Stir to combine and cook either on high for 4 hours or low for 6. After done cooking, shred chick with a fork, season to taste. Add to your favorite fun and top with some coleslaw!