I need help remembering the title of a movie.?

I saw this movie about a year ago, but the movie itself could be a few years old. It starts with a man who may be having some financial troubles receiving a phone call telling him that if he kills a bug, he will receive a small bit of money. He keeps getting calls telling him to do acts that get increasingly heinous for more and more money. I can provide more details, but I didn't want to spoil anything incase anyone finds that to be an interesting plot.