A birthday prank was a step too far for some fans.

In a post this week on his Instagram page, Chris Hemsworth celebrated his twin sons’ 9th birthday with a fun family photo.

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In the picture, Hemsworth is looking on as his wife Elsa Pataky and one of their kids push one of the birthday boys’ faces into a delicious-looking chocolate cake.

“Only one way to eat cake in this house and that’s to have mum slam your head into it face first!! ‘Hey mum I don’t like chocolate cake I prefer vanilla’ ‘oh really son, what about now’?” the “Thor” star wrote in the caption.

But some in the comments didn’t appreciate the humour in the photo.

“Why do people think this is funny?” one person asked, while another commented, “It’s so violent.”

“Why people smash their kid’s face in the cake is above my understanding but whatever,” wrote another.

Someone else said, “In my country [this is] done, but it’s very poorly [looked upon] because several accidents have already happened.”

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Others, though, defended the parents for the prank, with one person responding, “Violent? It’s a bit of play.”

“Those kids are gonna grow up able to take a joke not be some little fairy who thinks having their head dipped in frosting is violent,” said another commenter.

Another fan added, “Just a bit of basic humor….. they look like they are having a good time together.”

Hemsworth and Pataky, who tied the knot in 2010, share twins Sasha and Tristan, as well as 10-year-old daughter India.