What is the worst hack you've ever written? This is different from What is the worst code you've ever written?, because that, as I understand it, revolves around code later called worst because of ignorance.

hack: code written, knowing it is horrible code, for the sake of convenience, deadlines, working around another broken system or bug, etc., but not ignorance.

If you want, you can describe your co-workers' reaction, how bad your hospital bill was after showing them the code, if you felt disappointed in yourself for coming up with it or proud of yourself for coming up with a creative and clever solution.

This doesn't have to be shipped code, this could also be code written for personal purposes.