When you need to reverse a number's sign but decide to take the scenic route through Absurdistan... This function is the programming equivalent of using a nuclear submarine to cross a puddle. The code checks if d is negative, then uses Abs() to make it positive (reasonable). But if it's positive? It subtracts d*2 from itself—a galaxy-brain approach to multiplication by -1. What makes this truly horrifying is that this overcomplicated monstrosity was part of the UK Post Office's Horizon system that led to the wrongful prosecution of hundreds of postal workers. Real people went to jail because someone couldn't write d = -d . The tragic irony? The comment literally shows the correct solution right above the function. It's like putting "just use stairs" in the elevator manual, then designing a catapult instead.

Ah yes, the classic "stating the obvious" comment. The car door literally says "This DOOR is Blue" while being clearly silver/white. It's the programming equivalent of writing int x = 5; // this is 5 instead of explaining why x needs to be 5. After 15 years in the industry, I've learned that future you will hate past you for these comments. The real documentation we need is "WHY this door is painted differently" not "WHAT color it obviously isn't." Just like your code should explain the how, your comments should explain the why.