In 1977, The Flintstones, which had been in reruns on NBC earlier in the decade, made their first primetime appearance on the network with A Flintstone Christmas, the first holiday episode of the franchise in 12 years.
Fred (Henry Corden) & Barney (Mel Blanc) are out shopping, and Fred becomes perturbed when Barney drops a coin for every street corner Santa he meets. This runs counter to the 1965 (season 5) episode where Fred actually believed in Santa. "Who is the Real Santa Claus?" was previously used in a more contemporary special a few years earlier
Take note that Pebbles (Jean VanderPyl in a dual role) and Bamm-Bamm (Russi Taylor) are at least kindergarten age, or where they were for the short-lived Cave Kids series.
The whole idea of subbing for Santa would be done again with Johnny Bravo 20 years later, among others.