The child resents the threat and the lie attached. The child did not forget what you said two weeks ago. He is testing you. No one is in the same mood at all times. This was told as a joke on The Tonight Show , but it is often true.
Parents think that they are making things easier on themselves if they remain flexible.
This is not true. Children do not understand or appreciate being assessed a punishment that was previously unannounced. The same is true if a consequence was announced and not imposed when the rule was broken. Parents must learn to use the same consequence for the same behavior on good and bad days. If you know you are having a bad day, you must remember that your child's future depends on you being consistent and fair.