This paper presents an automatic coupling mechanism with mechanical overload protection for use in modular robotic systems. The genderless coupling incorporates a novel safety mechanism that disengages two modules at a pre-defined torque threshold. Several key design aspects allow the minimalist coupling to contain all functionalities within a compact cylindrical space. A detailed analytical model of the overload protection mechanism is validated by testing two materials and fabrication methods. We further present a functional prototype of the coupling with a demonstration of two modular robots driving towards one another, automatically connecting and disconnecting, detecting the connection, communicating in the process, and sensing the angle between them. The coupling as well as the embedded technologies and mechanisms present essential steps towards enabling fully self-reconfigurable robots combining modular and origami features, while advancing the process of introducing modularity into a wide range of robotic systems.