A sex bolt is really a pair of bolts which screw together. They are used to strongly attach something to an existing planar object. Like a door. Generally one bolt is male in the sense in that it penetrates into the object being you want to attach, but is threaded internally to receive another bolt. The second bolt can be of any type, and between the two of them they clamp the attached object in place.

Sex bolts are not necessarily used during the practice of kinky fun.