Robbie Williams once smoked a lump of rubber after mistaking it for cannabis.
The reclusive star – who also claims he can roll a joint, a cigarette containing marijuana, with one hand while driving - admits he was duped by a drug dealer, but decided to try it anyway.
He said: "Once I bought a lump of resin and it was rubber from someone's shoe, so I smoked it anyway. "I could do the whole process of rolling a spliff in one hand in a car while it was moving. It was the only Scout badge I ever wanted.'
The 'Angels’ singer – who is an avid believer in the existence of aliens – recently revealed a bad experience with LSD made him want to stab himself. Robbie, who was just 16 when he tried acid, said: "American footballs were coming out of the TV. So I decided to go downstairs and stab myself. Mum came out of her room and said, 'What are you doing?'
"I said, 'I'm just going downstairs to stab myself - do you want a cup of tea?'"
The 34-year-old has been admitted to rehab twice, the last time shortly before his 33rd birthday in 2007, when he was admitted to a treatment facility in the US for a dependency on prescription drugs.