Probabilistic mechanical fasteners are used to provide secure, reversible, and repeatable attachments in both nature and industry. Since the first observation of this mechanism in nature, which led to the creation of hook-and-loop fasteners, there has been a multitude of variations on the basic hook-and-loop design. However, few fastener designs have looked back to nature for inspiration in creating novel products or improving existing fasteners. Given the diverse probabilistic mechanical fasteners employed in nature, there is opportunity to further the research and development of these underdeveloped fasteners. To this end, we present a framework which describes the theory, design considerations, modelling, and mechanical testing required to study probabilistic mechanical fasteners. We further provide a comparison of the performance of existing probabilistic mechanical fasteners found in nature and industry as a reference for novel bio-inspired designs. Finally, we discuss current areas of application and future opportunities for fastener innovation.