1. Mix lime juice, olive oil, garlic and crushed red pepper in a bowl. Add shrimp, mangoes and pineapple. Toss well and season with salt and pepper.
2. Prepare a charcoal fire and let burn to a gray ash (or preheat a gas grill to medium). Drain shrimp, mango and pineapple and pat dry, reserving liquid. Thread on metal skewers, alternating shrimp and fruit. Brush with reserved liquid and season with salt and pepper.
3. Grill until shrimp is cooked through and pineapple is lightly browned, about 3 minutes per side. Serve warm.