1. Insert a wooden skewer into each shrimp.
2. Combine cinnamon, black pepper, salt, cayenne, brown sugar, and mustard; stir well to combine. Coat the shrimp with the spice mixture.
3. Place the shrimp and any remaining spice mixture in a zip-top bag. Refrigerate the shrimp at least 15 minutes and up to 24 hours.
4. Preheat broiler. Line a baking sheet with aluminum foil and arrange the shrimp on the baking sheet.
5. Broil shrimp in the middle of the oven until cooked, about 10 minutes.