DNA

After 10 years, the wife starts to think their kid looks kind of different, so she decides to do a DNA test. She finds out that the kid is actually from completely different parents.

Wife: "Honey, I have something very serious to tell you."

Husband: "What’s up?"

Wife: "According to DNA test results, this is not our kid."

Husband: "Well you don’t remember, do you? When we were leaving the hospital, we noticed that our baby had pooped and you said please go and change the baby, I’ll wait here for you. So I went inside,

Spoiler:

got a clean one and left the dirty one there."

Moral: Never give a man a job that doesn't belong to him.