1. Bring 2 cups water to a boil in a pan. Add couscous and 1/4 teaspoon salt. Remove from heat; cover and let stand 5 minutes. Fluff with a fork.
2. Heat 2 teaspoons butter in a large skillet over medium-high heat. Add garlic and scallions; cook 30 seconds. Add shrimp, and cook, stirring, 3 minutes or until they begin to turn pink.
3. Stir in beans, parsley, lemon juice, remaining butter, remaining 1 teaspoon salt, and 1/4 teaspoon pepper. Cook 2–3 minutes or until heated through. Serve with the couscous.