So true. Especially swimming and a flat tire. Everyone should know both.There are certain things in life (swimming, horseback riding, changing a flat tire, operating a firearm) that are quite simple but are quite embarrassing if you're forced into a situation where you need to do it but haven't done it before.
Firearms was just an example. I'm sure there are other things that maintain value well also. Gold comes to mind if you can get any.