 The series has attracted many celebrities . Robert Downey , Jr. telephoned the show production staff and asked if he could produce or assist in an episode 's creation , as his son is a fan of the show ; the producers subsequently created a character for Downey . Lauren Conrad met MacFarlane while recording a Laguna Beach clip for the episode " Prick Up Your Ears " ( season 5 , 2006 ) . She has watched Family Guy for years and considers Stewie her favorite character . Commenting on his appearance in the episode " Big Man on Hippocampus " ( season 8 , 2010 ) , actor Dwayne Johnson stated that he was a " big fan " of Family Guy . Johnson befriended MacFarlane after he had a minor role in Johnson 's 2010 film Tooth Fairy . R & B singer Rihanna has admitted to being a fan of Family Guy , as has pop singer Britney Spears ; she tries to imitate Stewie 's English accent . Spears , who was mocked for her personal problems in the South Park episode " Britney 's New Look " in 2008 , offered to appear in a cameo to hit back at the similar animated show , but MacFarlane declined , stating that he did not want to start a feud with the series . 
