Now there's a contradiction in terms. Rap music. Actually I kinda used to like rap, like Dylan's Subterranean Homesick Blues
Would that qualify as the world's first rap "song?"
No offense meant to those who like rap. I don't see the "art" in it.
Seriously though, gangbangers have been killing people long before rap. Hell Johnny Cash was singing about Cocaine blues and shootin' his woman probably before I was born.