Oh man this is awesome, the rapping is terrible but clever and kinda works, on the moon level it actually reminded me of Mr. Plinkett. The dialogue was great I never thought I'd read the words "diarrhetic death" but I'm glad I did. I liked the gameplay, though as one of the other reviewers mentioned my main strategy was to spam the rap button until I got to the moon. I don't know if it was intentional or not, but from the moon onwards I wasn't able to gain lives back by rapping.
Overall I loved this one.