In normal use, FLAME JOB references an elaborate, attention getting air-brush painting of "flames" on the gas tank of a motorcycle. Such completed work is called a "flame job".
In its derogatory use, "FLAME JOB" references a gay male who struts or sashays about in a flamboyant manner, trying to garner attention to his gay self.
Interestingly enough, FLAMBOYANT is defined as: 1. characterized by waving curves suggesting flames
2: marked by or given to strikingly elaborate or colorful display or behavior.
Tony: Fuckin' sick flame job.