This reminded me of a story about the launch of WebTV by Microsoft back in the 90s.

My memory is blurry but essentially the bug was in the signup or login code. When displaying an error to the user, the memory address to read the message from was pointing to an array of banned words. This lead to the user seeing no details of the error but instead just the word “f*k”.

Unfortunately the only reference I can find to it online is someone also trying to find it and failing: https://dotclue.org/archive/2006/12/002664/