These plugs were custom rigged for the feature film "Companion". The central spike was lightly spring-loaded. This allowed the spike to recess into the handle when pressed against the actors head, giving the appearance of the plug inserting. The collar around the spike was also replaced with a steel ring, allowing it to stick to a magnetic surface. This was used to create the effect of the humanoid character plugging itself in.
This one is easier to understand in video :)