Mike Tyson struggled with his lines during his cameo in The Hangover because he was "high on cocaine" during the shoot.
The boxer made an appearance in the hit 2009 comedy and his stint was so popular, he was hired to return in 2011 for The Hangover Part II.
However, Tyson has now revealed he was high on drugs when he filmed his scenes for the first movie, and credited his co-stars with helping him cope despite his raging personal problems.
In an interview on In Depth with Graham Bensinger, the former world champion admitted that "(during) the first Hangover, the guys just had my back so much. They carried me real good. I was a mess. I was overweight... I was a pig, high on cocaine. They had to know I was messed up. I couldn't talk. I had the cocaine talk.
"Those guys are just beautiful people. They had my back, and I appreciate that and stuff, then they asked me to come back (for the sequel) and I guess I am thankful to (the director) and all those guys."
Bradley Cooper, Zach Galifianakis and Ed Helms are all currently filming the third installment of The Hangover franchise, while Tyson is rumoured to be making his third cameo appearance.