I turned 40 in June. Planet Rock Afrika Bambaataa is the first rap song that i heard. I didn't know what it was. Then White Lines from grand master flash. Then "The Show" with Doug E Fresh then it was like the flood gates opened and it became difficult to keep up with them all.
A couple i can remember that stand out...
Rappin Duke Da Ha
Dana Dane Nightmares
Avid Stamp Collector - I really love 39 Cent Stamps