開心三響炮 (1985)

Original title: Kai xin shuang xiang pao

Once there are two detectives in the police force, Fatty and Lanky, they have been very, very good friends, that until the day Gigi comes to their department for work. Fatty and Lanky immediately go after her skirt. Fatty and Lanky must find Boss Sin. They try to get information from Sin's man Fairyman who considers himself the biggest lover in town.