Mike Tyson was unaware of his cameo in The Hangover as he was 'doing drugs' at the time

For almost anyone, you'd think having a part in a major movie would be a very big deal - but not Mike Tyson.

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"I met the guys in a club, they were in the VIP section and I said, 'This is where I normally sit, nobody's normally here,'" he recalled.

"So I went in there, I'm checking these guys to see what they're doing in my section.

"It was Zach, the other guy, and he said, 'We're going to be in a movie with you.' And I said, 'Yeah? When?', and he said, 'Tomorrow.'"

He added: "And I didn't know as I was drinking and smoking back then, doing drugs, so I didn't know I was involved in the movie.

"So eventually I had to go and do the movie and it was a success."

Indeed it was, and given the story of the film (the clue is in the title if you haven't seen it), perhaps it was quite fitting that Iron Mike was too drunk and high to know he was in the movie.

And the 56-year-old didn't let up on his intake when shooting began either.

"I was a mess. I was overweight. I was a pig, high on cocaine," he admitted.

"They had to know I was messed up. I couldn't talk. I had the cocaine talk."

Since then, Tyson has turned his back on cocaine and alcohol - and got into weed in a major way.

Tyson now has his own cannabis line, Tyson 2.0, and he wishes the drug had become a bigger part of his life earlier.

In fact, he wishes he'd smoked it his whole career.

Speaking to Yahoo Finance in October, he said: "My life was just miserable, I was out of control. I was fighting with everybody. If someone asked me for an autograph, I'd punch them in the face.

"I was just a mess, and then after I retired, I started smoking. What a mistake that was - I should have smoked my whole career. I should have smoked when I was fighting because it put me in this different state of mind.

"I'm very relaxed and the more relaxed you are, the better fighter you are at least in my case."