Cartman's dad can't be Chef, we already saw the, er, 'coitus interruptus' by Mr. Garrison, so we know that Chef never finished the job, so to speak.
But noone mentioned the mysterious appearance of Kyle & Ike's dad...
It was implied that he was also in the running..."How could you!"
Could they have a pudgy little racist brother? And then could odd-looking Ike be a little bundle of revenge on Mom's part, after a fling with Terrance? Or Phillip?
Ok, maybe I'm reaching...
M