Every once in a while you hear about a joke that someone made years ago that later turned out to be true. It happens more in Hollywood than real life, which leads one to believe that at least in some cases, the joke became the inspiration for the plot twist. This is fairly believable in the case of George Lucas, who made up the Star Wars plots as he went along. A bit of speculation from a the actor inside the Darth Vader costume in the first movie led to Darth Vader being Luke’s father. Several silly details from Mad magazine later showed up in the prequels. Coincidence? Maybe not.
Then again, not all these are Hollywood movie twists. A piece of fan fiction from 2014 had Taylor Swift and Tom Hiddleston meeting at the Met Gala and becoming a couple. The two stars met -at the Met Gala- and became a couple in 2016. The more stories you read, the more you suspect you might be in The Twilight Zone. Six of those stories can be found at Cracked.