everybody is a black body=??

i dont agree with this statement .a balck body purely and surely implies that it absorbs 99.99999% falling on it ,

and all other bodies are not black bodies but bodies which abosorb(or emit) less than this.

if u feel i m worng .plzz correct me. BUT I WANT SOME GOOD EXPLAINATION AND REASON FOR EVERY SENTENCE U HAVE GIVEN.

{my main question, explain how b=always constant for all bodies}