Mike Tyson was high on drugs when he met the stars of 'The Hangover'.

The 54-year-old former boxer had no idea he had signed up for a cameo in the 2009 movie - in which Zach Galifianakis, Ed Helms and Bradley Cooper's characters steal his pet tiger - and was unaware he was due to film the part the day after he met them in a nightclub.

Speaking to Tony Robbins, he said: ''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'.

''So I went 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.''

Mike previously admitted that he was high on cocaine during filming but credits his 'The Hangover' scene - where he punches Zach's character - with giving him a whole new set of fans.

He said: ''I was a mess. I was overweight. I was a pig, high on cocaine.

''One day I'm in a restaurant and the movie hadn't come out yet, but the kids must have seen the preview of me punching Zach.

''So one of those sightseeing busses went by and all the kids came off the bus and grabbed me, taking pictures and my friend says, 'I think we've got something here Mike' and I said 'Yeah, me too'.

''It's been different, it's changed ever since. When I go out and I meet younger kids that are 20 or 15 it's because they watched 'The Hangover' - they had no idea that I used to be a boxer.''