A farm burger is a slang term originating in Hamilton, New Zealand, around 2009. The term was used to describe a burger made by a student at the University of Waikato from different burgers on the McDonald's menu after a night of drinking cask wine. The student and his friends, as usual, ended the night at McDonald's and he couldn't decide what he wanted so he ordered one of each type of burger: a quarter pounder, McChicken and Fillet-o-fish. He was so hungry he couldn't wait to eat them separately so he put all the meat together on the same bun. His friends cheered him on and afterwards they named it the "farm burger" because it had had "all the animals of the farm" on it.
McDonald's customer: I'm very hungry, Got one of those burgers with all the meats? A farm burger
McDonald's cashier: Such a product does not exist, sir. I think you must have dreamed it.
McDonald's customer: Oh, then just give me a quarter pounder, McChicken and a Fillet-o-fish