I’ll never forget my self injury with a blackjack :)
There is something about injuring yourself with something like that that makes it seem even stupider, if that is even possible.
It is like that moment of sheepishness that almost every guy has experienced as a young boy, trying to cut something with a folding blade knife, only to have it fold and gash your finger between the blade and the body of the knife!
You had probably been warned about it, but...until you actually do it to yourself, the lesson doesn’t really stick in. Then...you never (or ALMOST never) do THAT again!
Hehe...in your case, were you just trying to see how it felt on your own head, and thought you would lightly whack it to find out? No WAY you thought, would that light blow cause any harm...:)