Prepare the marinade: squeeze the lemon and orange. Peel the garlic cloves. Mix everything with olive oil. Season with salt and pepper. Peel the shrimp, keeping the tail. Put in a shallow dish and cover with marinade. Let it sit for 1h30 in the refrigerator. Peel the grapefruits and prepare in quarters. Peel the mangos and cut into pieces. Set aside. Drain the shrimp and brown them for 1 minute on each side in a lightly oiled pan. Thread three at a time onto skewers. Add half of the mango pieces and brown for 2 minutes. Prepare the other fruits in a salad, add cress, and drizzle with marinade. Arrange on a skewer and serve.