Garfinkel claimed that these breaching experiments would more accurately be described as demonstrations because they illustrate the ways in which social rules and norms are created and sustained.
More to the point, these rules are taken for granted. Garfinkel notes that people use, sustain, and take part in creating these norms without being aware of it. He calls this knowledge "background expectancies." While a person does use these social rules and norms consciously, the reason they use such norms and rules is more subconscious, or in some cases, unknown; that is, until a person or persons engage in breaching experiments to expose the taken-for-granted-knowledge (and/or background expectancies) that we use in everyday situations and conversations.
In a sense, what Garfinkel is saying is that we speak and act with direct language but also with figurative language or social codes. For example, "How's it going" is interpreted as "How are you doing" - on a given day or in general. But the "it" in "How's it going" is, grammatically speaking, without a referent and could therefore mean anything at all. During a breaching experiment, a person might counter the question with "What do you mean by 'it'?" The object is to show what 'it' really is but also to show how we use social codes, rules, and indirect language without being consciously aware of it.
Such experiments/demonstrations also reveal that when someone breaches (violates, disrupts) a social code or rule, others will attempt to reestablish those codes and roles, even if this defies logic or ethics.
Stanley Milgram's Obedience Experiments are a famous example of how people will conform to such social codes and roles even at the expense of harming other people. In the experiment, a teacher was asked to shock the student when the student got a question wrong. The teachers were encouraged by the administrator of the experiments to continue to shock the students for answering incorrectly. Since the administrator represented an authority figure, the majority of teachers (taking for granted that they were only playing the role of being subordinate to the administrator) continued to inflict the shocks.
Those who would refuse to continue the shocks are the ones who breached the social roles of authority figure and subordinate. In fact, this was a voluntary experiment. It showed how people tend to automatically obey authority figures especially if they had some official title.
This "taken-for-granted-knowledge" is not only evident in the ways we speak. It is also evident in the roles we play. In some ways, such knowledge, codes, and rules are necessary to facilitate communication. In other ways, such codes and roles can be used to suppress people and compel them to behave in beneficial or destructive ways.