Monopoly tried to sue a professor for making a parody game. The suit was thrown out because Parker Brothers had stolen the game themselves!
Monopoly has been keeping people occupied for hours at a time for several decades. While it may just be a board game, it can teach real-life economic lessons. Hence, one economics professors created a parody game called "Anti-Monopoly."
The story goes that Monopoly was created and patented by an unemployed heater salesman, Clarence B. Darrow, and then sold to game company Parker Brothers in the 1930s. Forty years later, General Mills, who owned Parker Brothers, sued the economics professor who created Anti-Monopoly.
However, the suit was repealed because it turns out that the Parker Brothers nor Clarence B. Darrow actually invented Monopoly. It was actually created by a Quaker named Lizzie Magie in 1903. It was originally called "The Landlord's Game" and was meant to teach people about the unfairness of land ownership. She probably should have added in something about the unfairness of stealing someone else's ideas.