Place 2 large boneless, skinless chicken breasts in Crockpot.
Add ½ cup BBQ sauce, 2 tablespoons Italian dressing, 1 packed tablespoon brown sugar, 1 teaspoon Worcestershire sauce, and 1 teaspoon salt to mixing bowl. Stir ingredients together until fully combined. Pour prepared BBQ sauce mixture over chicken in Crockpot, covering chicken breasts completely.
Secure lid on Crockpot and set time and temperature to 3 to 4 hours on HIGH heat. Flip chicken breasts over occasionally as needed to keep chicken covered in sauce.
After 3 hours, check internal temperature of chicken breasts with internal meat thermometer. Insert thermometer into thickest area of chicken breasts. Remove chicken from Crockpot once chicken reaches 160° to 162° Fahrenheit.
Transfer cooked chicken to cutting board or large bowl. Let chicken rest 3 to 5 minutes, then use 2 forks or hand mixer to shred chicken to desired size pieces.
Return chicken to Crockpot. Gently stir chicken into BBQ sauce, making sure to cover shredded chicken completely.
Set heat to LOW heat. Simmer BBQ chicken 15 to 30 minutes, or until some sauce has been absorbed.