A bronze avalanche is usually given during revenge sex, or final sexual encounter when breaking it off with someone. A bronze avalanche is the act of a guy ejaculating inside someone else, then immediately unloading their bladder and pissing inside as well. The piss provides the bronzing, and the jizz provides the avalanche.
Person A: "Yo, this chick did me so dirty, I got her back good"
Person B: "What you do to her?"
Person A: "Gave her a Bronze Avalanche!"