He's smoother than a nose on a newborn calf.
Ken Curtis began as regular Festus Haggen in episode, "Prairie Wolfer" (Jan.18,1964).
Guest Star Elizabeth MacRae was a regular on the series, Gomer Pyle U.S.M.C. as Gomer's girlfriend, Lou Ann Poovy. This was her first of 4 episodes as Festus' girlfriend April, the others were: "Once a Haggen" (Feb. 1,
1964, "Now That April's Here" (Mar. 21,1964), and "Circus Trick" (Feb. 6,1965)
This is Festus' first episode. You can already see foreshadowing of his upcoming regular status when Dillon asks what his plans are.