Originally SDU is the Hong Kong equivalence of a SWAT team.  The title of 飛虎出征 – SDU: Sex Duties Unit (Blu-ray release 2013-12-5) is based on a wordplay of the term SDU.  This comedic movie tells the story of four SDU police officers sneaking to Macau to find prostitutes.  Naturally things go wrong at every point.  Although the movie is reasonably entertaining for Hong Kong audience, another movie 大丈夫 (Men Suddenly in Black) (2003), with a similar subject from the same director, is far better in the richness of the story, cast, style, and originality.