Well, I agree that you should not be 100% truthful to your kids since our role is to slowly introduce them to the real world, but you should hear the stuff that my mother-in-law comes up with to convince my 3 year old to do things: "I have to leave your house now because my doggy is lonely and misses me" or "we can't play with that toy right now because the toy is tired and wants to go to bed" or "its time to leave the playground because the policeman just called me up and said its time to go."