Santa Claus and the Easter Bunny and the Tooth Fairy. All nonexistent. All entirely gratuitous lies, except for Santa who was sometimes used to extort a few weeks of goodness in December.
Everyone in America is Equal and Can Do Anything They Set Their MInds To. Growing up in the South, I unconsciously added "as long as you're white" to this proposition. I hung on to that one into adulthood. That lie made me feel bad that I never amounted to anything when, truth be told, I did pretty well for cracker spawn. Come to think of it, I probably wouldn't have tried as hard as I did if I hadn't been lied to about my prospects.
A Job Well Done is its Own Reward. Having been stiffed on a few well done jobs, I can tell you that this is definitely not true. Payment for a job well done is the reward. And if you do the job badly and still get paid, that's sometimes even better.
This is Going to Hurt Me More than it Hurts You. Really? Now that I'm an adult and have been really pissed off at some kids whom I mostly love, I can tell that there must be some real satisfaction in flogging them.
The Policeman is Your Friend. This one I figured out pretty early was bollocks. When I became a policeman, I learned just how unfriendly cops really are.
Always Whittle Away from Yourself.