There are a lot of old school emcees who give much respect and credit DJ Hollywood as being the first rapper, while others have a different story. According to Kurtis Blow, he makes a strong claim as Hollywood being the first to do it and mentions how he would go "off the dome", what we now call "freestyling", and never wrote his rhymes down.
The popular party phrase; "Throw ya hands in the air, and wave'em like you just don't care..", is one of the many creations by DJ Hollywood that other rappers and DJs still use to this day. He was the DJ for Lovebug Starski in the early 1980's and also released his own single "Shock, Shock, The House" in 1980.
There's an interview of DJ Hollywood on the Hip-Hop 101 Blog from 2007. Go check it out to get a more in-depth feel of who he is and how he got his start.