After graduating from college, Ng Yun Fat joined a real estate company as sales executive. He is a smart young man always looking for opportunities to make money. His girlfriend, Fong Mei Lai, is a pretty girl with a simple mind.
Ng Yun Fat's mother, although now living in the city, still keeps the habits of country life. One day, Yun Fat's colleagues wanted to visit his new flat and have a house-warming dinner. When they arrived, they realized that Yun Fat's mother is an old-fashioned woman still living with old traditions. They also found her cooking to be very non-hygienic. Due to these psychological effects, they all ended up with diarrhea.