A spicier way to say ridiculous. It is believed the first person to have coined this phrase was probably some ex-indie kid who tried starting a whole new sect of his own. Guess that didn't turn out too well.
Hey brah, that dope ain't gonna sell for that rudunkulous price, ya dig vato?
An adjective to describe something that is worthy enough to be called exceedingly preposterous that is deserves an even more absurd name than ridiculous.
Person 1: Oh my god! Did you hear that Ashley Olson is dating Lance Armstrong?
Person 2: That is absolutely ridonkulous he's almost twice her age!