Merle Haggard'Grandma Got Run Over By a Reindeer' has been infiltrating radio air waves for 30 Christmases now. And while almost everyone may be familiar with the song, initially recorded by married (and since-divorced) couple Elmo and Patsy Shropshire, the story behind the love-it-or-hate-it tune is finally coming to light. The legendary holiday song was actually inspired by a legendary country singer.

The writers of 'Grandma,' Randy Brooks and Elmo, met while playing in local bands in 1979. Randy, who mostly wrote songs for fun, counted on artists such as Dolly Parton, Bob Dylan and Johnny Cash for inspiration for his songs. But it was while listening to Merle Haggard's Christmas hit, 'Grandma's Homemade Christmas,' and realizing halfway through the song that the woman in the song passes away, that the idea for the novelty hit was born.

"I got angry and said, 'Merle, that's so unfair to do to people,'" Randy tells ABC News. "If you were half the songwriter you think you are, you would admit in the first line of the song that grandma was dead ... and then if you could come up with three verses and a chorus you'd really have something. So that was my exercise, a parody of Merle Haggard's song."

Randy says he didn't have to look far for inspiration once he had the idea for the lyrics. "My grandmother did like to drink herself happy on occasions, and we did worry about her leaving the house," he says with a laugh.

Neither Randy nor Elmo imagined the response it would get when a DJ in San Francisco heard the song and played it for the first time. "I wasn't thinking beyond getting some cheap laughs in a bar," Randy admits. "That's what I was writing songs for, to sing novelty songs as comic relief for my band, and the more punchlines I could put in the happier the audience was. I certainly wasn't thinking of a national audience."

Thirty years later, it looks the song is here to stay. "There were so many years that I didn't know whether it was going to come back or not," Elmo says. "So now when I hear it, I'm always grateful that it did come back, and people are beginning to say that this song is one of the great classics and I'm happy to know that."

'Grandma Got Run Over by a Reindeer' also inspired an animated TV special. It has been covered by dozens of artists over the years.