Add shrimp to large resealable freezer bag.
Add oil and gently squish to coat the shrimp.
Add the Cajun seasoning and, again, gently coat the shrimp.
Add the lemon juice and mix again.
Remove excess air, seal and freeze.
Soak bamboo skewers for 30 minutes.
Thaw shrimp.
Add shrimp to the skewer and BBQ over medium heat for 5-7 minutes turning once, until shrimp is cooked through, pink and curled.
Alternatively, shrimp skewers can be cooked under the oven broiler for 5-7 minutes, turning once.