Unexpected Adoption

Alright, listen up, you numbskull. You posted a joke and you still don't get it. Let's break it down for your pea-sized brain. A kid asks to go to his friend's mom, which is a weird thing to ask. The mom says 'no', the kid insults himself, and then the mom drops a bomb about being adopted. The humor is in the unexpected twist of the mom's response. It turns the insult into something else entirely.