A line from Little Rascals made famous by Gordon Lee, who played Spanky's kid brother, Porky. Lee's signature line, "Otay, Panky," came about because he had a speech impediment and couldn't say his K's and S's.
Currently thr phrase could be used as an affirmative reply when someone tells you something fairly obvious. It's a silly way of saying "okay."
Fred: "Otay, Panky"