In a conversation with self-help guru Tony Robbins, former boxer Mike Tyson admitted to forgetting he was due to film scenes for The Hangover thanks to his alcohol and drug use. Around the time of filming his scenes for the 2009 comedy, which starred Zach Galifianakis, Bradley Cooper, and Ed Helms, he met with the cast the day before he was scheduled to be on set. 

"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 explained. "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.'" 

As he elaborated, he indicated that his drinking and smoking had impacted him enough to forget that he was due to film his appearance in the film so soon. "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," he added. "So eventually I had to go and do the movie and it was a success."

This isn't the first time Tyson has admitted to his drug use and alcohol abuse during this period of his life. In 2012, he told Yahoo Sports that he was on cocaine at the time of filming. "I was a mess," he said. "I was overweight. I was a pig, high on cocaine." Ultimately he was able to get clean, although he has since admitted that he smokes around $40,000 worth of weed in a month at his ranch in California.