Asian movie where poor family tutors someone from a rich family and then they kill eachother

Theres a joke about fumigation and how theyre too poor to pay for it so they open up their window to let it in, (im basing this off the ad), then someone from the poor family gets a job tutoring someone rich fron a rich family, and I THINK THAT THEY KILL EACHOTHER I DONT REMEMBER THAT FOR SURE.