"Luke, I am your father." It's one of the most famous movie quotes ever, right? Not quite. That line isn't actually in the Star Wars movies. Darth Vader's real line is, "No, I am your father." If that's definitely not how you remember it, you're not alone. This is just one example of the Mandela effect.
The Mandela effect is a phenomenon where many people collectively misremember events, historical facts and pop culture, like so many fans confusing that iconic Star Wars line.
New examples of the Mandela effect, from the spelling of Berenstain Bears to the existence of a 90s movie called Shazaam, commonly sweep through social media. Some people are so surprised by their bad memories that they start conspiracy theories like an alternate timeline to explain it.