After 10 years, the wife starts to think their kid looks kinda strange 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, you noticed that our baby had pooped, then you said: " Please go change the baby, I'll wait for you here. " So I went inside, got a clean one and left the dirty one there.”

Giggles!