Cogwheel headband

Two strips of tape with velcro ends studded with a series of triangular brass teeth as might be found on a cogwheel. Each person involved lifts the majority of their hair out of the way vertically and scrunchies it into a top knot, wraps the tape horizontally around their head at temple level, fastens it with velcro and proceeds to mesh with their partner and turn their head satisfyingly, following the course of the strip as a bonding activity.

It won't work for threesomes.