1. Place sour cream, dry mustard, pepper, salt, garlic powder and Worcestershire sauce in a large mixing bowl.
2. Mix on low speed with an electric mixer for 3 minutes.
3. Add mayonnaise and green onion.
4. Mix on medium speed for 3 minutes.
5. Fold in crumbled blue cheese being sure to mix well.
6. Place plastic wrap over bowl and put in the refrigerator 24 hours or until ready to serve.
7. Serve as a dip for chicken wings.