In life, the really important lessons we all need to learn are often passed down to us by relatives, friends and people who are just generally wiser than us.
From not taking sweets from strangers to never, under any circumstances, getting a wet-look perm (thanks to so many people in the '80s for illustrating the folly of that one), our loved ones and ancestors are frequently called on to share the lessons they learned the hard way.
But what about the more obscure things that might not come up in everyday life?
For example, there are only a few people alive today who know the importance of getting all the words out in the right order when you're getting sworn in as US President, and they didn't think to pass that info on to Barack Obama in 2009...
Or how about the lessons that are so obvious, we assume we don't need to explain them to anyone? Like matching your foundation to your skin colour or not parking a car on the street just as a piano is being winched up into a flat directly above it.
Thankfully the global stage of public humiliation/wonder that is the internet has enabled us to view many of the great untaught life lessons and life hacks on camera - sometimes just at the moment people learn them.
It's strange how willing some people are to share these lessons, even when they're pretty personally embarrassing. We can only assume they don't want us to have to go through what they did...