Widely-cited article listing misconceptions programmers carry about time — e.g. 'a month always has 30 or 31 days' (not true) or 'a month always begins and ends in the same year' (Ethiopia starts the year on September 11, breaking this). Inspired a broader 'falsehoods' repository covering other domains like email (e.g. the fact that you can have multiple @ signs). Hasiński uses it as the framing device for his own list of LLM falsehoods.