Funnyman Jack Black is still pinching himself after his comedy idol Eric Idle agreed to be a part of the School Of Rock star's inaugural Festival Supreme.

The former Monty Python star will join Adam Sandler, Zach Galifianakis, British comedians The Mighty Boosh, Sarah Silverman, Fred Armisen and Black's comedy rock act Tenacious D at the event, which will hit Santa Monica, California in October (13), and Black admits he could not believe how easy it was to book him.

He says, "I can't even believe Eric Idle said yes. We asked him thinking, 'He's not gonna do it' - and now he's doing it."

Black tells, "I just sent him an email or a love letter, basically telling him about my favourite songs that he's written, and I said, 'This is going to be a special day and a celebration,' and that there was going to be amusement park rides and good food to eat and that people are going to be kicking out the jams all day and it wouldn't be complete without him. And he bought it."