The Mandela Effect
Incorrect memories are sometimes shared by many people, leading some to irrationally speculate that they’re the result of some form of alternate reality shifting. So-named from the common misconception that Nelson Mandela died in prison in the 1990s (he actually became president of South Africa and lived until 2013). In many cases, the false memory is being conflated with a similar incident (Stephen Biko was revered much like Mandela, and he did die in prison), and then are communicated and reinforced among members of a group.