An item not actually on the McDonald's restaurant's food menu. When one wishes to confuse, embarass, belittle, or otherwise make fun of a McDonald's employee, they are to order one large McPenis Filet. This item is normally ordered from the drive-thru menu, however, excessive confusion can be added by walking inside, gesturing up toward the menu above the employees as if the item is actually up on the menu, and then ordering the aforementioned McPenis Filet.
"Hello there, welcome to McDonald's! Can I take your order?"
"Yeah, give me a coke, small fry, and a McPenis Filet."
"Alright, that's a Coca-Cola, child's-size fry, and what was that last item?"
"A McPenis Filet...give me a big, juicy, McPenis Filet."
"I'm sorry, sir?"