A lock for a food container of the type having a lower front flap and a partially-overlapping upper front flap, comprises an elongated body that has a tapered front end, a rear end, and a transverse stop disposed between the front end and the rear end. The front end of the elongated body has at least one angled resilient flange that has have a distal end adapted to flex towards the body temporarily in a compressed position when under force. Thereafter the at least one flange springs back to a natural position once inserted through front flap apertures of the container, inhibiting the removal thereof without breaking a perforated section or an otherwise frangible section of the container, thereby leaving evidence that the container has been opened. An embodiment that includes a clasp for receiving the front end of the body with a bag therebetween is also disclosed.