Place 1 pound shrimp (peeled and deveined) in a medium bowl. Add 2 teaspoons Cajun or Creole seasoning, 1 teaspoon paprika, 1 teaspoon Worcestershire sauce, 1/2 teaspoon brown sugar, and 2 cloves minced garlic. Stir until the shrimp are evenly coated.
If time allows, let the coated shrimp sit 5 minutes at room temperature to allow flavors to meld (optional).
Heat 4 tablespoons butter in a large skillet over medium-high heat until melted and beginning to foam.
Add the shrimp and any remaining seasoning mixture from the bowl to the skillet in a single layer.
Cook the shrimp 2 to 3 minutes per side, turning once, until they are opaque, pink, and cooked through (no translucent center).
Remove from heat, sprinkle with chopped fresh parsley, and serve with lemon slices for squeezing.