In the synectics pdf they mention that
"to make the familiar strange is to distort, invert, or transpose the everyday ways of looking and responding which render the world a secure and familiar place."
We make the world a secure and familiar place by the concepts we hold and cherish, the content of our consciousness, that finally make meaningful our selves, the people around us, the whole world. Concepts are abundantly provided by family, neighbourhood, town, city, nation, country, school, workplace, religion and so on.
You distort, invert, transpose the concepts upon which your consciousness is based. It is a mental exercise where single or multiple concepts are questioned. Their correctness and validity is doubted. It can also be connected to a particular problem seeking solution.
In the same document it is mentioned
"It is a conscious attempt to achieve a new look at the same old world, people, ideas, feelings, and things."
Such an exercise is bound to change our consciousness conceptual content. It could lead to a new viewpoint. We might see our selves, the people around us, the world in a new light.