Insane guitar playing. Usually used to describe someones guitar playing during a super fast and awesome sounding solo.
The two words do not have to necessarily be put together into a sentence. Look at examples.
Jimi Hendrix's righteous chops will turn you brain into mush.
From the sponge bob movie:
My precious helmets!
-- His chops are too righteous.--
The helmets can't handle
this level of rock 'n' roll.