Abstract: A thermoplastic closure of the type having an annular internally threaded skirt; an annular skirt extension permanently attached to the skirt adjacent the skirt's lower extremity; one or more discrete arcuate sectors of the skirt extension being configured as flaps permanently affixed to the main body of the skirt extension at a first end being the trailing end during the unscrewing operation and frangibly connected to the main body of the extension at a second end being the leading end of the flap during the unscrewing operation; a container engaging tooth extending towards the container from each flap adjacent its second end; a hinge on each flap intermediate its first end and the container engaging tooth; the container engaging tooth being adapted to override a trigger tooth adjacent a container neck during the running up of the closure onto the container but to lock against the trigger tooth during the unscrewing operation; such locking adapted to break the frangible connection between the main body of th