The actor-and-comedian wants to practice the mythical 2,000-year-old sex positions book during his permanent separation from estranged wife Katy Perry. A friend told the Daily Star newspaper: "Russ picked up a copy of the Kama Sutra at the beginning of summer. "He has set himself the challenge of reading it and acting it out before summer ends. It`s been a long-term aim of his. And now he`s single he`s going to go for it." The Hindu book is famous for describing the art of making love with 64 illustrated sex positions that have names such as The Camel`s Hump, The Crab and The Wheelbarrow. The source added: "Russ told me `It`s the professional`s version of that `Fifty Shades Of Grey` book`. "He gets bored easily and likes to keep himself entertained. He`s always setting himself little challenges to keep his mind occupied." They continued: "He said it would be the ultimate sexual challenge. But to be fair to him he wants to educate himself on the philosophies of the book as well as the enjoyment."