Even if your child is prone to fudging the truth, it's important that you don't label him a "liar." That label can be seriously damaging, especially as your child learns to live up to his new identifier. Instead, let him know that while lying isn't cool, it doesn’t define him. Avoid saying things like "I can't trust you," which could do long-term damage to your parent-child relationship. Instead, try "I understand why you didn't want to tell the truth, but when you lie, it hurts my feelings. Can you try and be more truthful in the future?"