Ref is a shortened word for "reference"
"Kanye ref" itself gives the meaning when someone makes a sentence that include a word that references a Kanye West song.
Guy1: I'm scared of flashing lights
Guy2: FLASHING LIGHTS??? KANYE REF
Usually used in a sentence when somebody makes a sentence that relates to Kanye West (such as like his songs, things he did and etc.)
Guy 1: Bro, can you give these roses to my mom?
Guy 2: ROSES?! KANYE REF!!!!