Shia LaBeouf spoke out about his horrific method acting technique that left Jon Bernthal stunned

Shia LaBeouf has lifted the lid on his scary acting technique that left co-star Jon Bernthal stunned.

The Transformers actor, 38, had just got fired from a play with Alec Baldwin when Brad Pitt messaged and asked if he wanted to star in a WWII drama alongside him.

Titled Fury, the David Ayer-led film came out in 2014 and was centred around US Army Staff Sergeant Don 'Wardaddy' Collier (Pitt), who was in charge of a Sherman tank crew on a dangerous mission behind enemy lines in Nazi Germany.

His team included the likes of Boyd 'Bible' Swan (LaBeouf), Grady Travis (Bernthal) and Trini 'Gordo' Garcia (Michael Peña).

The crew are faced with confronting the horrors of war while maintaining their humanity in the process.

Meanwhile, on the actual set, it seems LaBeouf was keen to impress as Bernthal called it a 'wild experience'.

In an interview shared by Talent Agency Guide, the actor recalled: "And then we're in this makeup trailer getting ready to do this movie and I just made friends with all these armours, and we're like putting fake mud on our faces and like it just feels like 'oh man, like this can't be it you know'.

The cast of 2014's Fury (Stephane Cardinale/Corbis via Getty Images)

"So I see Brad Pit in the mirror and I'm thinking like 'how do I motivate my boys,' you know, 'how do we make this more, how do we get further?'"

Fully against the idea of using fake mud and props, he then used a knife to scar his face to make a point to Pitt, the lead actor.

"I wanted more and we had already fallen in love at that point, like really bonded, and so I'm like rubbing blood on my face, partly for the character, but also partly like [to] motivate the troops, you know.

"And then I'm like, I went and kissed him on the face, and that wasn't enough, they kind of laugh at me like I'm an idiot. And they think it's like ridiculous."

LaBeouf then decided to use a pair of pliers to pull one of his bottom teeth out.

"And then I went to the grip department, I got some pliers and I ripped my tooth out and spit blood all over the mirror and everybody's like 'oh this is f**king crazy'," he added.

"And if I wasn't around a bunch of people who loved me, I might have gotten fired, you know, but what it did to us was, it like it's game time."

To make things as real as possible, LaBeouf then claims the rest of the cast refused to go in the make-up trailer for the remainder of filming.