Abstract: A container lid for placement on the mouth of a container is designed to prevent the unwanted removal of fluids from the container. The container lid includes a beverage dispensing chamber having an open first chamber end, a closed second chamber end and at least one chamber sidewall extending from the first chamber end to the second chamber end. The beverage dispensing chamber includes a spout chamber which includes an open end and a closed end connected by a wall. The wall includes a valve slit which forms a valve flap having a memory closure mechanism to render the valve slit effectively impermeable to fluid absent force upon the valve slit.