Preheat an outdoor grill for high heat and lightly oil the grate.

Place shrimp in a glass bowl. Pour lime juice over shrimp. Stir in cilantro and garlic. Set aside.

While the shrimp is marinating, slice jalapeno peppers in half and remove seeds. Cut onion into chunks.

Tuck 1 shrimp into a jalapeno half. Wrap with 1 slice of bacon and thread onto a skewer. Repeat with remaining shrimp, jalapenos, and bacon, adding onion chunks in between every 2 or 3 shrimp.

Place skewers on the preheated grill. Cook, flipping every 4 to 5 minutes and basting with lime juice if desired, until shrimp are pink and bacon has browned, 15 to 20 minutes.