noun which may take the genitive case particle 'no', noun
Guinness record-level; world-record-class
Colloquial expression used to describe something so extreme or impressive that it seems worthy of a Guinness World Record. Often used hyperbolically.
His eating is Guinness record-level.
The length of this line is world-record-class, isn't it?
Compound of ギネス (Guinness, from the Guinness World Records) and 級 (class, rank). A modern colloquial coinage.