His first movie, a low-budget Hong Kong period comedy called Where is Mama's Boy (2004), was released in January 2005. Hung played a good-natured village kid who sells Chinese pancakes to pay his mother's medical bills. His character gets discovered as a singer, and helps a woman protect her business from her jealous, conniving elder sister. In the film, Hung played opposite veteran Hong Kong actress Nancy Sit and parodied his own American Idol performance with the song "Siu Beng" (Cantonese) ("Chinese Pancake"), an allusion to his American Idol audition song, "She Bangs." Despite solid financial backing and the involvement of Nancy Sit, the film was a box office flop.
