Hollywood funnyman Jack Black was such a hellraising teenager, his parents were forced to withdraw him from school.

The SCHOOL OF ROCK star admits to a string of behavioural problems as a young student, including drug abuse and stealing, which saw him admitted to a specialised school and undergoing therapy by the time he was just 15.

He says, "I took some drugs in high school. I was doing cocaine and I was too young. What the hell was I doing? And I sniffed some glue. I was on a rampage.

"Also, there was this guy at my school who wanted to kill me 'cos I made out with a girl he liked, so by about 15 I was in full meltdown."

And Black confesses he only agreed to life-changing therapy sessions out of childish curiosity - but is relieved his inquisitive nature saved him from a disastrous breakdown.

He says, "Some of the more intense kids were going in every day and I was, like, what happens in there? So I went in one day and said, 'Can I have therapy?' and he said, 'Sure, sit down.'

"I don't remember exactly how it went down, but I started confessing...and I told him about how I stole money from my mom to get coke, and I just cried and cried and cried my eyes out.

"Came out a different guy one hour later."