In a recent interview with Tony Robbins, Tyson said it was only when he bumped into the film’s stars on a night out that he realised he was due to appear in it the next day.
“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 said.
“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.’
“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.”
Tyson has previously spoken about how he was under the influence of drugs while filming. In his most famous scene, the boxer knocks out Galifianakis’s character, Alan.
“I was a mess. I was overweight. I was a pig, high on cocaine,” he told Yahoo! Sports. “They had to know I was messed up. I couldn’t talk. I had the cocaine talk.”
Tyson went on to star in the movie’s 2011 sequel, The Hangover Part II.