I remember this movie I watched somewhere around 4 years ago. It was in cantonese. This guy that was called Mr Bo. assassinated someone and put his head in a bowling ball. As the police try to solve the case Mr Bo ends up helping one of the rookie cops. I am starting to feel like I just dreamed it up… But I remember it being awesome and want to watch it again
Legendary Assassin (2008) – http://www.imdb.com/title/tt1236370/
I agree with Cotopaxi. It is definitely Legendary Assassin.