Step Brothers fans stunned after finding out truth about 'Sweet Child O’ Mine' car singing scene

Step Brothers is that film for most people who grew up in the noughties, but there’s something you probably don’t know about one of its iconic scenes.

Whether it was the white poo, the urge to be rolled into a tiny ball, or getting revenge for someone’s nut sack touching your drum kit, the film had a tonne of hilarious moments - but there was one that stood out as the best.

That’s right, it’s the 'Sweet Child O’ Mine' car scene when Brennan Huff’s brother, Derek, comes to visit with his obnoxiously perfect family.

The comedy, which came out in 2008, follows the story of Brennan (Will Ferrell) and his mother Nancy (Mary Steenburgen) who moves into the Dobag residence with Dale (John . Reilly) and his dad Robert (Richard Jenkins).

From then on, Brennan and Dale navigate being mortal enemies, before bonding over their shared hatred of Derek, and their love of the same strange pop culture references.

However, it was when Dale stood up to ‘the one they call Derek’, we were introduced to just how much of a pain in the a** Derek truly was.

This was only furthered when he insisted on having a family a cappella session in the car, and complained to his wife that her voice was ‘flat’ and that her numerous vocal lessons had been a waste of time.

That’s when Derek decided to ‘save’ the performance by giving one of the most majestic vocal solos of all time.

Except, it wasn’t real.

OK, before you freak out and re-watch it, yes, the scene was real.

But actor Adam Scott didn’t actually sing at all - he lip synced it.

This devastating confession was revealed by co-star Kathryn Hahn, who played Derek’s unhappy wife, Alice.

During an appearance on Capital Radio on Thursday (19 September), she was asked about the iconic scene and revealed what really went down.

She explained that even though her part and the kids’ parts were all live, because of how much Scott needed to embody that ‘boyband’ voice, it was decided that he would lip sync while an actual boyband pop star took over.

Hahn said: “His voice had to go to some real, you know, boyband places, and so there an actual boyband singer right outside the car.

“And Adam lip synced.”

However, she commended him for his ability to lip sync so well that the performance was entirely believable.

Calling it ‘incredible’, Hahn said that he snapped right into character and that’s probably why we all loved the moment so much.

Fans of the movie were not ready to hear those words and were stunned to learn the truth.

One person commented: “He was LIP SYNCING??!!”

Another wrote: “This lip sync is pure gold! Adam nailed it, and the vibes are hilarious!”

Someone else, who was clearly devastated, added: “I absolutely love Kathryn Hahn. she has broke my heart telling us Adam was lip synching.”

And Scott himself has also addressed not singing during an appearance on Jimmy Kimmel Live.

He revealed: "So I was lip-syncing to someone that was singing live right outside the windshield."

I suppose he was good, but he wasn’t quite ‘the songbird of our generation’.