In a large pot, bring water to a boil and add the shrimp. Cook for 2-3 minutes until they turn pink and opaque. Drain and rinse under cold water to stop the cooking process. Set aside.

In a large mixing bowl, combine the ketchup and lime juice. Stir until well mixed.

Add the cooked shrimp, avocado, cucumber, red onion, cilantro, and jalapeño (if using) to the bowl. Gently fold the ingredients together until everything is evenly coated with the sauce.

Season with salt and pepper to taste. Cover and refrigerate for at least 30 minutes to allow the flavors to meld.

Serve chilled with tortilla chips on the side.