Nice of teetotaller throwing streamers for celebration (8)
I believe the answer is:
confetti
But I can't explain it at all! Could you help me understand?
(Other definitions for confetti that I've seen before include "Alternative to rice" , "Small pieces of coloured paper" , "Stuff to throw at weddings" , "Paper used at weddings" , "Celebratory scraps of coloured paper thrown at weddings" .)