My daughter would be so upset if I lied. True to many GT's, she is so into "what is right". When she was in the basket at the grocery store as a little girl and I turned around to get something, she would say "Mommy" and point to the picture on the basket that I was breaking the rule. She memorized them as soon as she could sit up and I got in trouble every time I broke the rules. I have to say that it is very difficult to shop with a small child and follow all those rules.
My son was like that when he was younger, but he was able to see that there are some times when lying might be necessary and a matter of survival, like when his dad was 13 and had to lie about his age so he could get a job so he could have enough to eat.
We sometimes use his mental age instead of his actual age.