"Mexican Phenomenon"

One day, during free time at office, I argued with a friend.

Friend   : Mexico is in Europe, right?
Me        : You're kidding, right? For God's sake, who on earth doesn't know where Mexico is??
Friend   : That's not like something we all have to know
Me      : Yeah, but Mexico is a famous country (It's not like we were talking about Mauritania, or Republic of Sierra Leone, or Federated States of Micronesia. Can you even guess where these countries are?) Didn't you have Geography at school? I bet you're the only one who doesn't know it.

I confidently challenged him and ended up asking some people at our floor about whether they know in which continent Mexico is. And the result surprised me! Out of 8 people we were asking, only 4 people knew it. Yes, just half of it! The other people weren’t sure or even had no single idea about it. I baffled. I lost words.

Perhaps, we were all ever be in the same situation, when we thought a common thing for us is common thing for worldwide. The truth is, it is NOT. Ever since I realized that, I always call such circumstances when people judging others for not knowing something as “Mexican Phenomenon”.

At times, we unintentionally (or do we?) say thing like “oh come on you don’t know this kind of thing?” or in Indonesian “yaelah kayak gini aja nggak tau”. Where in fact, there is no standard for people to know certain things. There are too many variables; point of interest, sensibility, environment, etc.

Because if there are too many standards, then there is no standard.

I begin questioning, do “common knowledge” really exist? And what about "common sense"?