Add the mayonnaise, sour cream, white vinegar, sugar, salt, and pepper to a small bowl.
½ cup mayonnaise, ½ cup sour cream, 2 tablespoons white vinegar, 1 tablespoon granulated sugar, 1 teaspoon salt, ½ teaspoon freshly ground black pepper
Whisk the ingredients together until smooth and well combined. Set aside.
Place the pasta, crab meat, salad shrimp, peas, and celery in a large bowl. Spoon or pour the dressing over the salad ingredients.
1 pound medium pasta shells, 8 ounces crab meat, 8 ounces frozen cooked shrimp, 1 cup frozen peas, 1 cup finely chopped celery
Toss the salad until the dressing coats the ingredients evenly.
Chill for 1 hour, then add any garnishes or additional seasoning before serving.