What is a blind contour? It's an exercise where a person draws the contour of a subject without looking at the page, instead you fix your eyes on the outline of the model or object then imagine that your pencil point is touching the object instead of the paper. So you are tracking the edge of the object with your eyes, without taking your eyes off the object while simultaneously drawing the contour slowly. You want a steady continuous line without lifting the pencil or looking the paper or looking at the page.
As you do this, keep convincing yourself that the pencil point is actually touching the contour.
Why it's good to do blind contour drawing
This technique improves your drawings because it causes both senses of sight and touch to work together. Blind contour drawings may not produce a good drawing. It helps the eye and hand to work as a team so this is an exercise about process and not about product.
For the form part of this exercise, I found it helps to use your memory
of how objects feel and apply it as the same time.
Also I found this exercise great for concentration and a good laugh too :)