Monkey Ball from hell. I honestly wish each and every person involved in creation of this level would die a horrible death. No, I wish them all to lose persons they love the most in incredibly painful ways and I want them to know they are being punished for indulging their sadistic urges when building this particular I-Ninja level. Hours and hours of time spent, hundreds and hundreds or retries - no use.
EDIT: I take some of it back, I did it!