The season finale for the second season of The OC, the Fox soap opera, was a melodramatic cliffhanger. Ryan Atwood discovers that his brother, Trey, had tried to rape his girlfriend, Marissa. The two argue, then begin to struggle. Marissa walks in on the fight and begs Trey, who is winning, to stop hurting his brother; when he doesn't, she pulls out a gun and shoots him. It is not until the following season that the viewer learns whether or not Trey survives.
As the gun goes off, the soundtrack swells with a strangely out-of-place song by Imogen Heap. The camera cuts back and forth between the three characters' terrified faces as the strains of "Hide and Seek" drown out the incidental sound effects.
In April of 2007, Saturday Night Live aired a short film that spoofed this scene. (The SNL clip was originally titled "The Shooting," but it was soon popularly nicknamed "Dear Sister," and is now known almost exclusively by that name.) In the SNL short, a young man named Keith writes a letter to his sister. Another man, Dave, asks him what he is doing, then inexplicably shoots him as Imogen Heap's "Hide and Seek" cues up. The scene becomes more and more preposterous as other friends, police officers, and even the sister herself all enter and shoot or are shot by the people who are already there. Each time the gun goes off, the Imogen Heap song starts up afresh and the reaction shots are recorded in overdramatic slow motion.
The film short became a wildly popular Internet meme that circulated throughout YouTube for the rest of 2007. Not only did the original OC and SNL clips get a lot of attention, but Internet wanks with too much time on their hands started to pull violent scenes from other movies to give them the Dear Sister treatment. A gunshot or some other sudden death would be taken out of context, the characters' reactions to the attack would be substantially slowed down, and "Hide and Seek" would be cued up at the most melodramatic moment.
Violent, climactic scenes in movies like The Departed, 300, Lord of the Rings, Star Wars, and others, were all Dear-Sistered at some point, proving if nothing else that even very good directors can sometimes lean a bit too heavily on clichés when filming a reaction shot. Needless to say, the Imogen Heap song became funny in itself, simultaneously creating pathos and bathos.
Some of the amateur YouTube directors got hilariously experimental with their Dear Sister meta-spoofs. Children attack each other with Super Soakers in slo-mo as "Hide and Seek" plays. Elmer Fudd adds new drama to Wabbit Season. My personal favourite is the Dear-Sistering of a shooting in the old Nintendo game called Duck Hunt: the Imogen Heap song is cued over a badly animated eight-bit duck, falling in slow motion.
The SNL clip can be hard to find, since Imogen Heap's record label did not provide clearance for the use of the song on the Internet. If you want to see it, you basically have to keep searching for it and then catch it before it's taken down. However, the original OC finale that started the whole meme is usually available; as of now it can be seen here. A YouTube search on the words "Dear Sister" will turn up dozens of fan-made parodies.