In a medium saucepan, combine the beer, garlic, bay leaves and lemon slices. Bring to a boil and then lower heat to simmer for 5 minutes or until garlic is soft. Add the shrimp and then the cajun seasoning. Cook for 4 to 5 minutes turning the shrimp if need be for even cooking. The shrimp is done when both sides are pink and opaque. You can drain the shrimp or serve as is in the pan with the beer broth. Serve with slices of lemon, drawn butter or hot sauce if you like. Tip: If serving with melted butter, mix with half lemon juice for all the flavor without all the calories.