A cap and container assembly includes a container having a base and a side wall extending upward from the base. The base and the side wall define an interior, and the side wall defines an opening leading to the interior. A cap moves with respect to the container between an opened position in which the opening is exposed, and a closed position in which the cap covers the opening. A tab projects outward from the cap and has a bottom surface. A spacer projects from the container side wall at a location beneath the tab when the assembly is in the closed position. The spacer bends inward towards the container in response to application of a sufficient force, to move from a locked position that blocks the bottom surface of the tab, to an unlocked position to expose at least a portion of the bottom surface of the tab.