Paul Rudd says his friendship with Green Day's Billie Joe Armstrong is the reason that the singer appears in film This Is 40.
Armstrong cameos in the movie as himself while Rudd plays a husband who is constantly fighting with his wife.
The film is written and directed by Judd Apatow who is also behind such hits as Knocked Up and The 40 Year Old Virgin.
The actor was speaking to Newsbeat's Natalie Jamieson.
This Is 40 is released in the UK on 14 February.