Justin Theroux said he blacked out and woke up on the ground in New York City after being hit by a vehicle, and at one point while in the hospital he was prepped for brain surgery

Justin Theroux is recounting a scary skateboarding accident that landed him in the hospital.

While appearing on Monday's episode of The Ellen DeGeneres Show, the Mosquito Coast star, 49, played a game with host Ellen DeGeneres and Stephen "tWitch" Boss in which he revealed one wild fact about himself mixed in with two lies. The first truth Theroux revealed was that he once was hit by a van while skateboarding in New York City.

"That's a true story," he said. "... I got hit by a van and woke up with people all around me. I clearly blacked out for, I think, a long time. There was a woman over me weeping [and] there were two men holding my arms so I wouldn't touch my head. The woman was screaming at me, 'Who are you? What's your name? What's your phone number?' trying to get in touch with someone."

Theroux said he had temporary amnesia when he woke up on the ground, unable to recall his own name in the moment.

"It was as if someone had asked me 'What is an umbrella?' and I forgot the name of umbrella, but it was myself," the actor explained. "I had no clue who I was. I mean, I knew I was me, but I couldn't remember my name and I couldn't remember my phone number."

“The Mosquito Coast” star Justin Theroux makes an appearance on “The Ellen DeGeneres Show” via video chat airing Monday, May 3rd.
Credit: Michael Rozman/Warner Bros.

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Theroux said he "then gradually started to come back" while they waited for the ambulance to arrive — over an hour later.

"This is kind of the New York hilarious part of it: the ambulance took about an hour and 20 minutes to get there. I was lying on the pavement and people are now kinda getting bored with this guy with blood pouring out of his head," he recalled. "Finally the EMT shows up over me ... He turns back to his partner, who I guess was still back in the truck, and he goes, 'He's not dead.' "

The Leftovers actor said that the first responders told him in the ambulance ride to the hospital that they would have shown up "quicker if we knew you were still alive," laughing about the anecdote with DeGeneres.

“The Mosquito Coast” star Justin Theroux makes an appearance on “The Ellen DeGeneres Show” via video chat airing Monday, May 3rd.
Credit: Michael Rozman/Warner Bros.

"It got worse," added Theroux. "I had a concussion. Then I went into the hospital that night and they had to keep me overnight for observation; they gave me all these brain scans and things. ... A guy wakes me up in the middle of the night and he says, 'We gotta get the doctor in here from Jersey, we think we noticed something on your CAT scan.' "

"It's like two in the morning. Then they shaved my head and prepped me for brain surgery," he continued. "I go, 'Oh, okay.' Then they make you sign all this paperwork and I'm thinking like, 'I gotta call somebody! There's no one to call!' So I sign my life away on these papers, then the doctor finally gets there from Jersey, and he comes in, sort of rumpled hair, and he looks at the CAT scan and he's like, 'This a thing with the scan, it's not blood on the brain. Go back to bed.' "

"I spent about half an hour waiting just to go to brain surgery, but it was nothing," said Theroux. "I had a nice big bald patch in my head. Couple stitches and I was discharged in the morning."

Theroux previously told Men's Journal about how skateboarding used to be an integral part of his daily workout routines.

"In my 20s, I almost never hit the gym, but that was mainly a result of a much more active lifestyle in New York, where I was almost always walking, on a bicycle or a skateboard to get places. So in that sense it was mostly cardio," he said. "Nowadays, I try to mostly work with simple weights, but at a clip with very short rests in between sets in an effort to get a metabolic workout while maintaining muscle."