The origins of one of Elvis Presley’s biggest hits remains somewhat of a mystery – if not at least murky.

In a 1957 interview, Presley admitted he doesn’t write songs, save for one time he came up with an idea for a hook: All Shook Up.

“It’s all a big hoax, honey. I never wrote a song in my life. I get one-third of the credit for recording it. It makes me look smarter than I am. I’ve never even had an idea for a song. Just once, maybe,” he admitted.

Asked when, he said, “I went to bed one night, had quite a dream, and woke up all shook up. I phoned a pal and told him about it. By morning, he had a new song, All Shook Up.”

‘All Shook Up’ Hits No. 1 in the UK

On this day 69 years ago, All Shook Up hit No. 1 in the United Kingdom after previously reaching No. 1 in the United States. Presley hit No. 1 in the U.S. with his Heartbreak Hotel, but All Shook Up was his first No. 1 hit in the UK.

But was it really his song?

Otis Blackwell is given the writing credit, but actor David Hess claims he initially recorded the song under the stage name David Hill.

“It was my idea. I have to give credit to Otis Blackwell…he took the song and made it something. I was lucky enough to record it first. My idea, Otis wrote it,” he claimed.

All Shook Up stayed atop the the U.S. charts for nine weeks, proving to be his longest-running No. 1 single. Rolling Stone put the song at No. 361 in a list of the 500 greatest songs of all time.