By Tessa Berenson
May 18, 2015

The closing song in the Mad Men finale Sunday night was the famous Coca-Cola jingle “I’d Like to Buy The World A Coke,” but Twitter is trying desperately to figure out who the “I” is.

Is it Don or Peggy?

Some people thought that Don’s trip to the hippie retreat wasn’t enough for him to escape his true calling as an ad man, inspiring him to come up with the Coke pitch:

But others thought it was Peggy who came up with the song while Don sheds his identity as a Mad Man in California:

Or maybe it was both of them working together:

In real life, of course, the song was actually the brainchild of a man named Bill Backer, a creative director at McCann-Erickson. But getting in on the social debate Sunday night, even Coca-Cola thought it was Don:

Read Next: ‘I’d Like to Buy the World a Coke’ Was the Perfect Way to End ‘Mad Men’

Write to Tessa Berenson at tessa.berenson@time.com.

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