Ctrl+Z Undo

Here's a thought I had in the shower just now. If you could un-invent anything, what would it be? Once un-invented, that thing would play no more part in the history of man, and anything it's done previously is erased.

My first thought was weaponry. But then I figured that if we hadn’t invented the gun we’d probably only have come up with some other devilishly fiendish way of killing one another.

So I’ve though of something else. Not telling what yet. What do you think?