Almost all (not to say all) existing humanoids have not been designed with the ability to change their endeffectors (head, feet and hands) on-the-fly. Inspired by the toolchanging mechanisms in robotics automation and manufacturing, we propose an end-effectors changer mechanism suitable to humanoids. This letter explains why enabling humanoids with such a technology is important and why existing tool-changer mechanisms are not adapted. The proposed changer mechanism is not actuated. Yet, it does not require human intervention to assist the change of end-effectors. We assess our mechanism through a comparative study with existing tool-changers and demonstrations with the HRP-4 humanoid. We claim that our idea could be a new turn in the design of future humanoids and open perspective to modular sizing of robots. The proposed mechanism can possibly apply to animaloids to some extent.