What does "a $ $" mean he said it at the end after the other guy?

Did he complete the other guy's word to say "pathetic a $ $" or is it two different insults? You just call someone a $ $ alone?[Audio]

Question

What does "a $ $" mean he said it at the end after the other guy?

Did he complete the other guy's word to say "pathetic a $ $" or is it two different insults? You just call someone a $ $ alone?[Audio]

Answer

Yes. 
Ass is a stand alone insult.
Behaved like an unthinking donkey.