the first (and possibly only) full rap song i have memorized is "sucker mcs" by run dmc.  on take a bite outta rhyme, lords of brooklyn and everlast turned it into a song.  on "in the beginning there was rap" wu tang clan covered it.  if you go over to youtube you can watch an original performance from soul train.  but probably my favorite performance that isn't run dmc was at the vh1 hip-hop honors where the beastie boys covered it.  now 20 years after the release of their second album, paul's boutique is being remastered and released.  head over to beastieboys.com for more information