He's asked to escort his rock 'n' roll idol from London to Los Angeles, and that is not an easy task.
Russell Brand plays the out-of-control rocker. He loved getting to live out his own superstar fantasy, even though that profession wasn't one of his original childhood dreams.
"When I was a kid all I wanted to be was an assassin. That dream never came true. Well I did assassinate one person, but other than one assassination gig it has been unfulfilled. Having failed as an assassin, I thought I would try to be a stand-up comedian," said Brand.
Hill and Brand had an easy time blending their comedy styles, which included quite a bit of improvisation.
"I think when you're working so closely with someone you know their rhythms and instincts," said Hill. "You can learn more about how you can set them up and how they are setting you up. It is really a fun experience."
Hill also riffed with actress Elizabeth Moss.
"I shocked myself at how much fun it was," said Moss. "It was great because you can do no wrong."
The film is rated-R for its two hours of sex, drugs, and rock 'n' roll. And for that, Hill makes no apologies.
"I think we have a responsibility to the audience, when you make a big R-rated comedy," said Hill. "You never wanna say I was too scared or have any regrets when you look back."
"Get Him to the Greek" is in theaters now.