In the third season episode I Married Marge, Homer Simpson spoils the biggest plot twist in science fiction film history to an entire line-up of eager threatre-goers when he exclaims "Who would have known that Darth Vader is Luke Skywalker's father?" Not only is it a great Homer moment, showcasing just how absent-minded he can be (and that's putting it nicely), it's also a joke that was considerably ahead of its time. Though you all understand today how annoying ruined plots can be, this episode pre-dates modern cries for spoiler alerts online by several years. There is actually a second Star Wars reference in this episode as well, when Homer tells Marge that she's as pretty as Princess Leia, and as smart as Yoda. It's Homer's foible that fans remember most, however. Add your own favourite Star Wars references from The Simpsons below!