The most quintessential, uproarious Thanksgiving episode of a sitcom remains “Turkeys Away,” the WKRP in Cincinnati masterpiece of bird-dropping pandemonium that first aired in 1978. Four decades later, at least among those of a certain age or those possessing a certain amount of Thanksgiving pop-culture knowledge, it remains a touchstone. That’s partly because the jokes still hold up and partly because it ends with a perfectly quotable mic drop of a last line, spoken by the late Gordon Jump as clueless radio station manager Arthur Carlson: “As God is my witness, I thought turkeys could fly.”