After 10 years,The wife starts to think their child looks strange so she decides to do a DNA test.
She finds out that the child is actually from completely different parents.
Wife: "Honey,I have something very serious to tell you."
Husband: "What's up?"
Wife: "According to the DNA test results, this is not our child."
Husband: "Don't you remember ? When we were leaving the hospital we noticed that the baby had wet it's nappy and you said, "Please go and Change this baby, I will wait for you here". So that's when I went inside, got a clean one and left the dirty one there."