Get Him To The Greek (2010)

Genre: Comedy
Starring: Russell Brand, Jonah Hill, and Sean Combs
Plot: A record company intern is hired to accompany out-of-control British rock star Aldous Snow to a concert at L.A.'s Greek Theater.

http://www.imdb.com/title/tt1226229/
http://en.wikipedia.org/wiki/Get_Him_to_the_Greek