He's known for his hulking 6ft 5in frame and signature squeaky clean bald head.

But fans might be surprised to know that Dwayne 'The Rock Johnson' isn't bald by genetic predisposition but out of choice according to Daily Mail.

The 44-year-old star's explanation came about after a twitter account for Showtime TV series A Season With shared a GIF of Johnson with curly brown hair.

'Why I luv GIFs. I'm not bald because I went bald. I'm bald because my hair is a cross between an afro and hair from a Lama's ball sac #TheU,' Johnson wrote.

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Fans found the revelation hilarious with one user replying: 'Hahahaha I love you Dwayne'

Unable to visualize the comparison Johnson was making, another fan replied: 'Oh great. Now I have to google a llama's ball sack.'

Another user reassured the Ballers star that his natural locks looked great, writing '@TheRock There's nothing wrong with your hair.'

It seems the actor made the choice to go hairless around 2010 when he was last spotted rocking a dark buzz cut.

Before acting Johnson was a college football player for the University of Miami, where he won a national championship on the 1991 Miami Hurricanes football team.

He later played for the Calgary Stampeders in the Canadian Football League and was cut two months into the 1995 season.

He then embarked on a career as a professional wrestler like his grandfather, Peter Maivia, and his father, Rocky Johnson.

The action star is currently promoting The Fate of The Furious as well as Baywatch and was spotted at CinemaCon last week answering questions about the upcoming movies with his co-stars.