In the case of a lie you can promise the kids ice cream or slurpy for no reason at all. You then pack them all up getting them all excited and then drive down to the local dairy queen or 7-11. right when you pull up and park turn the car back on and start driving home when they ask what your doing you can say "oh sorry, I lied!"
Of cource after they've calmed down explain why you did this cuase otherwise they might just be bad for revenge.
