Step 1Crumble 2 of the blue cheese packages into a bowl. Mash together the cheese and mayonnaise with a fork until blended. Stir in the sour cream and yogurt. Add the vinegar, 1 teaspoon of salt and white pepper to taste. Crumble 1 1/2 packages of the blue cheese into the dip, stirring to combine. Place the dip in a serving bowl. Break up the remaining half package of the blue cheese and sprinkle over the top of the dip. Cover and chill until ready to serve.
Step 2Season the chicken with salt and pepper to taste. Roll in flour to coat.
Step 3Fry the chicken in 2 tablespoons of butter and 2 tablespoons of oil over medium heat in a large skillet until browned on all sides and the meat is no longer pink around the bone, about 20 minutes. Fry in batches, if necessary, adding more butter and oil as needed. Drain on paper towels and keep warm (if frying in batches).
Step 4Melt 1 cup (2 sticks) of butter and combine with the pepper sauce. Dip the chicken legs in the mixture to coat; serve with the blue cheese dip.