look up any word, like kappa:
 
1.
1. Noun: Referred to as the 'The Prime Rib'; equivalent definition to the phrase 'the illest'; "the bees knees"

2a. However, can be used as an adjective in which 'prime rib' refers to something that is 'cool, tight, or sweet/distinctively awesome'. Synonyms include: dope, crack, fresh

2b. In any situation, derivation of phrase can be used.
Esp. to describe a female's admirable characteristics.
Just bought a leather toilet seat; that shit is the prime rib.

*No other examples are necessary.*
by Dr. Douchebag January 25, 2011
 
2.
Something that is cool and/or awesome and/or great.
Dude, did you see that flip he did? That was so Prime Rib!

If you can get those photos that would be Prime Rib.
by X3LA July 29, 2008
 
3.
A Synonym of the word "dank". Usually used when referring to some really really nice buds or "chronic".
"Dammnn mang, that Cali Kush is Prime-Rib!"
by Doda Dreje January 24, 2010
 
4.
the act of taking a humongus shit and then having ur girl stick her arm up your ass then make that bitch lick it off
it was really kinky one night so i told my girl to do a prime rib
by jeremyteddychris November 11, 2003