Rap music has its roots in Africa. Even before hip-hop or rap, the of West Africa narrated stories in a rhythmic way with drum beats. Rap came to America from the Carribean Islands (which has large African population). Their musical culture has constantly influenced the changes in American music.
Slang in rap was commonly used by the DJs of African-American origin. They would shout loud on the microphones, "Clap ya hands" or "Are ya ready to party?". People loved to respond to these questions and hence, slowly and steadily these slangs became popular.
The first big rap single that took America by storm was "Rapper's Delight", by Sugarhill Gang in 1979. This song revolutionized the rap music. The single was a great commercial success and producers were finally ready to produce rap records. Many new rap bands like, Run-DMC came up and found numerous fans. There were also people like, Kool Herc who would shout, "Yo this is Kool Herc in the joint-ski saying my mellow-ski Marky D is in the house." People loved his style. Rap had caught attention very quickly.
