Clean, devein, and peel the shrimp leaving the tails on
Chop the fresh parsley leaves
In a zip-top bag, add chopped parsley, 1/2 teaspoon lemon juice from one of the slices, olive oil, red pepper flakes, salt, and pepper. Close the bag and mix everything with your hands
Add the shrimp and gently massage it into the marinade so all of the shrimp is covered. Place it n the refrigerator for 1-2 hours. Do not exceed 2 hours.
Remove the shrimp from the marinade and discard the excess.
Brush the three halves of lemon with olive oil and grill, cut-side-down, for 3 minutes. You can grill these at the same time you are grilling the shrimp.
Skewer the shrimp on the skewers and grill on a medium-hot grill for 2-3 minutes per side.