^Honesty = Authority. How many children have had years worth of
  guilt and nightmares because they were told their dog or cat ran
  away or disappeared? "It's my fault that she ran away! I closed
  the door on her when she just wanted a pet." "I forgot to feed
  her" "If only I did this, she wouldn't have run off" - these
  kinds of thoughts circle around children's minds and torture
  them for years, all because a parent or aunt or uncle or
  grandparents thought they were "sparing the child's feelings" by
  not speaking the truth. Yes, your kids will think you as a
  horrible person for killing or throwing out their beloved pet
  without their permission, but they'll believe when you have
  other important news to tell them.

  Once they say, "I don't believe in Santa Claus", do you really
  continue trying to convince them that he is real? They're just
  playing along with you after that and you've lost your
  authority. Honesty = authority.^