In a small bowl, mix your chopped onions and lime juice together, and let stand for about 10 minutes
In a large bowl, toss together the cooked shrimp, tomatoes, cucumber, celery, jalapeno, salt, and black pepper. Then, proceed with adding the onion and lime juice and mix.
In another small bowl, make the dressing by whisking the tomato juice cocktail, ketchup, chopped cilantro, and hot pepper sauce.
Pour the dressing over the shrimp mixture, tossing until all the ingredients are well coated. Finally, fold in the avocados.
Cover and chill thoroughly, at least 1 hour to 1 day ahead!