Wash squash and trim off the ends. Cut them lengthwise down the center and carefully scoop out pulp from center. Place on baking sheet with centers facing up.
Meanwhile, in a medium size skillet, heat oil. Add onion, celery, bell pepper, and garlic. Saute for 2 to 3 minutes until slightly tender. Remove from heat.
In a medium bowl, combine shrimp, breadcrumbs, parsley, salt, pepper, and red pepper. Mix well. Add vegetable mixture and mix well.
Scope shrimp mixture into the center of each squash. Bake for 15 minutes or until shrimp are pink. Serve warm and enjoy!