The act of simultaneously pooping and ejactulating. Term comes from the combination of the words jizz and feces. This usually happens when something is so exciting and/or arousing that it causes one to not only ejaculate, but also shit oneself. Fizzing can often be accompanied by loud outbursts, moaning, and hurried trips to the bathroom.
Rubbing the pussy so hard and fast that the ladies pussy juice starts to look frothy and white as if an alka seltza has been placed just inside the lips.