One of the stranger bugs to show up in CD Projekt Red's award winning The Witcher III Wild Hunt, would see a noblewoman in a red dress follow Geralt around wherever he went. Whether he was hunting down enemies, strolling through the streets of a city or listening to quest dialogue, she'd be there, extolling his virtues.
That's perhaps the most hilarious part of the bug: that she was a big Geralt fan. She's call him a champion, calling for him to live forever and telling everyone within ear shot what a great guy he was.
And she is/was completely indestructible. Players have tried everything from setting off enormous explosions with her at their heart, to having her trampled by some of the game's nastier beasts.
And yet she continued to stand, telling you how awesome you are.
If you enjoyed that aspect of the game, consider not updating to the latest version of it, as CD Projekt Red has now patched her out of the game for good.
Admittedly for most people this was likely rather annoying and must have killed some of the game's immersion and tension at the worst of times - it's hard to imagine death as only a hair's breadth away when an invincible dilettante is standing up to more than you can as the world's greatest Wticher.