I just saw this on DVD and I honestly haven't laughed so much in a long time. This is a very funny, very silly, very stupid movie, one that is a parody of various other Hong Kong films (and a few non-HK films as well, like Pulp Fiction and the Transporter).
The main character played by Ronald Cheng, is a slacker of sorts, who suddenly is told by a trio of beautiful women that he is actually an undercover cop, but has apparently lost his memory. He's enlisted to infiltrate the organization of a triad boss, also played by Ronald Cheng (though this isn't obvious, the two characters look a lot different).
He does this for a while, but then apparently in effort to parody a bunch of other movies, it takes some very strange plot twists, basically involving his friendship with his large (somewhat Sammo Hung-esquire character) roommate, who has a crush on one of the lady cops.
But he's then drawn back into working for the police again as an undercover mole in the crime organization, and it starts to again parody a different sort of movie genre (which I don't want to spoil).
It's just really all over the place. It really is like Scary Movie or Airplane where they take a bunch of other movies and sort of make a pastiche out of them. If you haven't seen those movies, you won't get the parody aspect of it, but there are a numerous sight gags and just the main character acting dumb. By no means high brow comedy.
There are some action scenes, but these are parodies as well. While the action scenes are extremely well done and impressive, they are very much over the top and clearly meant to parody action movies. Especially cool is the bullet camera parody.
Don't expect a serious movie out of this, in terms of plot or characters. The plot makes little sense because so many elements are parodies, and the characters similarly are taken from other movies. Check your brain at the door. The opening sight gag making fun of Initial D clearly tells you to.
