Dafy is the quality of something being a dope ass mothafucka (daf). This can apply to wide range of nouns and objects. For instance, the President, a car, or even an idea for an invention can be "dafy".
"We went to the mall looking for fly swag and came out with some seriously dafy shit."
Potential female sex partner: "Wow, see Aymeric over there; he's dafy!"
P. Diddy: "Oh this song right here is DAFY!"