Juice lemons and limes and place the juice in medium sized bowl.
Devein and remove tails from shrimp. Place shrimp in citrus juice. If shrimp are raw, allow them to marinate 45 minutes until "cooked" and they become pink and opaque.
If shrimp are pre-cooked, no need to marinate, proceed with the recipe. Dice tomato, red onion, jalapeno, cilantro, and avocado.
Whisk cocktail sauce or ketchup into citrus mixture.
Gently stir in all remaining ingredients.