Preheat the oven to 450ºF.

In a large bowl, combine the olive oil, garlic, and salt; mix well. Add the corn, peppers, scallions, and shrimp; toss until evenly coated.

Divide the mixture evenly in the center of four 14" x 18" pieces of foil. Wrap foil securely, leaving room for steam to circulate; seal edges tightly.

Place the packets on a large baking sheet and bake for 15 minutes, or place on a preheated grill and cook for 10 minutes. Open packets carefully, as steam may be released.