Nashville resident co-wrote Coke 'Teach the World' song

Consider yourself warned: "Mad Men" spoilers follow.

Why are millions of people suddenly talking about a Coca-Cola commercial from 1971? It was shown in the final minute of the series finale of "Mad Men," which aired on Sunday.

The ending was ambiguous, but many viewers surmised that the show's lead character -- advertising executive Don Draper -- was inspired to create Coca-Cola's iconic "I'd Like to Teach the World to Sing" TV commercial after meditating on a hilltop.

In real life, that spot was created by ad man Bill Backer, and he co-wrote its catchy jingle with several musicians, including British-born songwriter Roger Cook, who's been a Nashville resident since the '70s.

Cook also co-penned '60s-'70s hits "You've Got Your Troubles" and "Long Cool Woman (In a Black Dress)." In a "Story Behind the Song" interview with The Tennessean in 2013, he said he "learned to love" the tune over the years.