A tamper-proof container and cap assembly is provided, comprising a container having an upper portion and an outer surface. The container has a rim at the upper portion. The upper portion includes a flexible and detachable protrusion having a contact element and a break point. The container also has a cap having a base with an outer periphery and a skirt extending perpendicularly and outwardly around the outer periphery of the base. The cap has a hinge and a tap with a first and second slot wherein the first slot is capable of housing the protrusion, and the second slot has an interlocking device that mates with the protrusion. In an empty stage, the protrusion is positioned within the first slot. In a filled stage, the cap is placed upon the container and the protrusion is repositioned within the second slot and the contact element engages the interlocking device to form a tamper-proof seal.