If using wooden skewers, soak them in water for about 1½ hours before grilling.
Peel the shrimp if the shells are still attached. Rinse under cold water and pat completely dry.
Season the shrimp with salt and black pepper.
In a medium bowl, whisk together the olive oil, lemon juice, garlic, red pepper flakes, and parsley.
Transfer the marinade to a large freezer bag or shallow dish and add the shrimp.
Marinate for 20–30 minutes. Do not marinate longer than 30 minutes because the lemon juice can begin to break down the shrimp.
Preheat your grill to high heat.
Thread the shrimp onto skewers if desired.
Grill the Lemon Garlic Shrimp for 2–3 minutes per side until pink, opaque, and cooked through.
Remove from the grill and serve immediately with extra parsley and fresh lemon wedges.