CUT tops off peppers; chop tops, then refrigerate for another use. Remove seeds from peppers; discard. Set pepper shells aside.
MIX meat, rice, peas, and 1/4 cup each water and barbecue sauce just until blended; spoon into pepper shells.
COMBINE remaining water and barbecue sauce in slow cooker. Stand peppers in slow cooker; top with VELVEETA. Cover with lid. Cook on LOW 5 to 7 hours (or on HIGH 2-1/2 to 3-1/2 hours).
SERVE peppers topped with sauce.