I write bad haiku;
Computer makes it better.
Computer analysis of any given text input finds five- and seven-syllable fragments. The program can use these fragments to produce haikus itself (with mixed results) or sort the fragments so that we can construct haiku ourselves.
Wikipedia explains various rules to formally define the characteristics of a haiku. I've ignored all of these with the exception of the basic composition of three lines with five, seven and five syllables respectively.