Lying babies.

Did you know that the human being starts lying at the age of 6 months? Early form of lying: fake crying.

IN THE COMMENTS: Original sin! St. Augustine!

ADDED: Commenter Chris digs out the text from "The Confessions":

Then, little by little, I realized where I was and wished to tell my wishes to those who might satisfy them, but I could not! For my wants were inside me, and they were outside, and they could not by any power of theirs come into my soul. And so I would fling my arms and legs about and cry, making the few and feeble gestures that I could, though indeed the signs were not much like what I inwardly desired and when I was not satisfied--either from not being understood or because what I got was not good for me--I grew indignant that my elders were not subject to me and that those on whom I actually had no claim did not wait on me as slaves--and I avenged myself on them by crying. That infants are like this, I have myself been able to learn by watching them; and they, though they knew me not, have shown me better what I was like than my own nurses who knew me.