An anchor system for a hollow wall or ceiling includes an anchor portion having a flange and a penetrating portion extending from a rear surface of the flange. The penetration portion has a fixed sleeve extending from the rear surface of the flange and a pivoting locking leg connected to the fixed sleeve by a hinge. The fixed sleeve has a non-round opening extending longitudinally therethrough and the pivoting locking leg has a stub extending from a rear surface thereof to retain the penetrating portion rigid as the anchor is inserted into the wall or ceiling. A pin portion has a body including a flexible shaft and an actuating element extending transversely from an end of the shaft. The shaft tapers, near the actuating element toward the actuating element to define a transverse dimension. The actuating element has a heel at about a rear surface thereof When the pin is inserted into the opening, the actuating portion contacts the stub to separate the pivoting locking leg from the fixed sleeve portion and to pivot the pivoting locking leg portion toward an inner surface of the wall or ceiling. Rotating the pin engages the actuating element at the heel with the stub to lock the leg in place and the shaft flexes to accommodate rotation of the leg more than or less than 90 degrees to secure the leg against the inner surface.