Ask HN: Has software you've written ever bitten you IRL?

Reading this comment's 'fun story' about the time its author accidentally made 1M API calls to a $x/request service made me wonder if anyone else has 'fun' tales of times they automated something or otherwise wrote some software intended for fun, profit, or benefit; that had some unintended real-world consequence?

https://news.ycombinator.com/item?id=22212063