The lesbian equivalent of yaoi: doujinshi or anime fanfic featuring sexual encounters between female characters who, in the original series, would probably never dream of the idea.

Or, perhaps, the straight male equivalent of yaoi. For just as yaoi doujinshi (and slashfic) are written largely by straight women, yuri are written almost exclusively by heterosexual men.

There seem to be several yuri doujinshi involving the Dirty Pair, which should come as no surprise.

(Yes, strangely enough, Yuri can also be a person's name. It is a feminine name in Japanese (as in the case of the Dirty Pair character after whom the genre was not named), but it is a masculine one in Russian (as in Yuri Gagarin).)