Culture shock is that phenomenon where one experiences a custom that is outstandingly opposite of what one has come to expect, particularly in decency or behavior towards others. The cliché way to experience this is with food: how people eat (sometimes slurping is accepted and expected at a meal), what people eat, how food is prepared, and even when people eat. With shows like Fear Factor, and the ubiquity of the internet, I think this cliché is generally outdated.
There are other ways to experience culture shock: how people drive, shoving instead of forming an orderly queue, or the quality of life (good or bad) that is on display. Again, with movies stereotyping everything, these tend to be found in almost reverse fashion: "I cannot believe how nice everything is, I was expecting the place to be full of slums!".
Another reason to never really experience culture shock (as an American) is that The United States is also relatively diverse, and by moving around a bit, one can experience all sorts of varying views, procedures, and ways of treating others.
In four years of living abroad on two different continents, not much has really surprised me or given me what I understand to be culture shock. That changed recently, with the Dutch childcare fraud scandal that has dissolved the government. It really takes following the news and understanding a situation to find the differences in the structure of cultures. When one hears the title (as an American), I assume that it means that politicians were committing fraud; but as far as I can tell, it is that they were being too strict in trying to mitigate fraud, that honest people had to pay back benefits.
I cannot wrap my head around this concept (as it would be a story for a day, if it was ever uncovered in America), but it has changed my perception of government institutions. Rules are put in place, and there will always be errors, it is up to the society to determine if they would prefer those errors to end up in people who maybe do not need assistance to get some additional help, or to rule with an iron fist, resulting in some people missing out on assistance that they need. I think the latter should always be preferred; presumably (if the cabinet is now acting based on what the people want) the Dutch agree.