HEAT oven to 375°F.
DRIZZLE milk over bread in medium bowl; let stand 2 min. Add chicken, celery and 2 Tbsp. wing sauce; mix just until blended.
SHAPE into 30 meatballs, using about 1 Tbsp. chicken mixture for each; place on rimmed baking sheet sprayed with cooking spray.
BAKE 15 min. or until done (165°F). Meanwhile, combine sour cream and blue cheese.
PLACE meatballs in large bowl. Add remaining wing sauce; toss to evenly coat meatballs. Thread 2 meatballs onto each of 15 small skewers. Serve with sour cream mixture.