Men like to watch two lesbians making out. Women like to imagine two men making out. The two genders aren't that different after all.
http://en.wikipedia.org/wiki/Slash_fiction
Slash fiction is a genre of fan fiction. It focuses on the depiction of sexual or romantic relationships between two or more male characters, who are not necessarily engaged in relationships in the canon universe. While the term originally was restricted to fan fiction in which one or more male media characters were involved in an explicit adult relationship as a primary plot element, it is currently more generally used to refer to any pairing between male characters.
It is commonly believed that slash fiction originated within the Star Trek: The Original Series fan fiction fandom, with "Kirk/Spock" stories first appearing in the late 1970s generally authored by female fans of the series.
For example, Angel/Spike fan fiction within the Buffyverse: in the Angel DVD commentary for "A Hole in the World", Joss Whedon, the creator of Angel said, "Spike and Angel...they were hanging out for years and years and years. They were all kinds of deviant. Are people thinking they never...? Come on, people! They're open-minded guys!" as well as Spike saying "Angel and me have never been intimate. Except that one..." to Illyria in the episode "Power Play." Needless to say, this has been seen as a vindication of some fans who have been arguing this point since the characters met. Some people say they see similar evidence of such relationships in other shows such as Smallville, The O.C, Friends and House.
Real person slash (RPS) gained popularity with the rise of the pop music industry.[7] In particular, the popularity of boy bands in the late 1990s and early 2000s promoted the growth of RPS. These singing groups, like *NSYNC or The Backstreet Boys, had public personas that were carefully designed and marketed to their target audience of girls and young women. As these boy bands were famous for being 'packaged' rather than for the sincerity of their public image, many slash authors had few moral qualms about treating them much like fictional characters. Real person slash involves taking the celebrity's public image and creating slash stories with them.
Slash fiction, like other fan fiction, sometimes borrows the MPAA film rating system, using the labels G, PG, PG-13, R and NC-17 to indicate the amount of sexual content in the story. Not all slash fiction has explicit sexual content, although it should be kept in mind that if a story claims to be or contain slash and is unrated it is likely to be explicit. The interaction between two characters can be as innocent as holding hands or a chaste kiss. As the result of trademark issues over the use of the MPAA rating system, some fandoms have created their own rating systems. If a story contains themes which may offend or which some readers may find distasteful (e.g. rape, incest, BDSM, shota/underage characters, or even heterosexual sex) it is considered polite to include warnings in the story header.
The term 'no lemon' is sometimes used to indicate fanfiction stories without sexual content. Anything with explicit content may be labeled 'lemon'. The terms 'lemon' and 'lime' arose from the anime/yaoi fandoms. 'Lemon' refers to a hentai anime series, Cream Lemon. 'Lime' is sometimes used to indicate that the story contains only mild sexual content, similar to a PG-13 film.
，“lemon”有个更时髦的中文翻译，“和谐”， 
