Every once in a while, every programmer discovers weird bugs in the software he uses or creates. Compilers that seem to randomly pass or fail without changing code. CSS layouts that work flawlessly, but not after restarting the browser once. You know these issues no one can explain.
Andreas Zwinkau compiled a great list of some really weird bug stories, both software and engineering related.
I really like the one about Crash Bandicoot, which randomly corrupted the saves of the Playstation memory card. Turned out that the baud rate controller on the consoles' mainboard interfered with the timer crystal. Fiddling with the controller while the game saves has led to dropped bits which caused the data corruption. Setting the tick rate from 1000 Hz to 100 Hz before saving a game solved the issue. Can you imagine finding out, that this software bug you are hunting for weeks is actually caused by the mainboard layout?
So, what is that one bug story you can tell, that no one would believe if it wouldn't actually be true?