From Rap Dictionary
The Shower Posse is a Jamaican based criminal organization which is involved with drug and arms smuggling. Its home is in Tivoli Gardens in Jamaica, but it primarily operates in New York, New Jersey, Florida, and Pennsylvania, where it is one of the most powerful posses. There are differing reports on the origin of the name. One theory is that it comes from the promises of its associated politicians to shower supporters with gifts. Another view is that it is a reference to the gang showering opponents with bullets. The gang has a strong international presence among expatriate Jamaican communities in North America. In the United States a branch was founded by Vivian Blake and it had a prominent role in the New York City drug trade. The gang also has a large presence in Toronto, Canada. In 1989, former Shower Posse member Charles “Little Nut” Miller was charged with drug trafficking but agreed to testify against other gang leaders in order to receive immunity. In his testimony – in which he implicated himself in nine murders - Miller revealed his connection to the JLP as a “political enforcer,” as well as to the CIA, going as far to state that “the United States made me what I am” (Newsweek, July 13th, 1998)."