Niggaz With Attitude (commonly known as N.W.A.) were an late 80s/early 90s (and therefore I dub them to be old-school hip hop and therefore cool). What’s so great about this song is not only it’s message but you can actually understand what the hell they’re saying (bonus!). Without N.W.A. modern hip hop would certainly not be where it is today (i.e. as a music genre more or less accepted by the mainstream).

This song has some Australian-related trivia associated with it, as Wikipedia says:

In 1989, Australian radio station Triple J had been playing “Fuck tha Police” for up to six months, before gaining the attention of Australian Broadcasting Corporation management who subsequently banned it. As a reaction the staff went on strike and put N.W.A’s song “Express Yourself” on continuous play for 24 hours, playing it roughly 360 times in a row.