Whisk olive oil, lime juice, tequila, garlic salt, cumin, and black pepper together in a bowl until well blended; pour into a large resealable plastic bag. Add shrimp, coat with marinade, squeeze out excess air, and seal the bag. Marinate in the refrigerator 1 to 4 hours.

Soak skewers in water to prevent burning, at least 30 minutes.

Preheat an outdoor grill for medium-high heat and lightly oil the grate placed about 4 inches from the heat source.

Remove shrimp from marinade and shake off excess. Discard remaining marinade. Thread shrimp onto the prepared skewers, 5 to 6 per skewer.

Cook, uncovered, on the preheated grill until shrimp turn pink, 5 to 7 minutes, flipping once. Serve with lime wedges.