An Australian term for a gay dude. Vegemite is a brown paste that looks like poop commonly found in Australia as a kind of edible spread. Poop is found in the butthole. Gay dudes go into other dudes buttholes. They often come out with poop on whatever part of their body they used to enter the other dudes anal cavity. Thus when they "pack the fudge," they are in fact mining for Vegemite as well.
Bob: Yo so that dude is the biggest vegemite miner ive ever met.
Joe: Ya bro i know. hes completely gay. what a flamer.