Abstract: A container closure assembly that includes a base that is adapted to be connected to a container, a spout extending upwardly from the base, and a cap removably secured on the spout. The spout defines an interior and includes a nozzle, the interior of which is spanned by a membrane that includes at least one score line defined therein. The cap includes a ring depending from and frangibly connected thereto, and includes a puncturing mechanism depending downwardly from a top thereof. Rotation of the cap in a first direction breaks the frangible connection between the cap and ring and causes the puncturing mechanism to puncture the membrane. In a preferred embodiment, the membrane includes a pair of intersecting score lines that tear when the membrane is punctured. In another preferred embodiment, the container closure assembly includes a leash that connects the cap and ring and that has a thickness and a width.