Nobody really believes Cartman is serious about having his first kid until he shows up in South Park with an infant. Kyle is stuck hauling the diaper bag over his shoulder, complete with sixty different compartments, so he never knows which one has the pacifier.
"Look at little Fatass junior."
"Don't call my baby fat you poor piece of shit!"
Stan peers at the pink bundle in Cartman's arms incredulously.
"Are you sure she's not a boy, dude?"
"Excuse me?" Kyle snaps.
Cartman sniffs. "She has his vagina."
"I can't believe you really have a kid," Stan says. "On purpose."