In the UK, in particular in the 90's, a Nugget was a term used amongst Heavy Metal fans to describe a fellow Metal fan who is only a fan supercially at surface level. They would often not grow their hair long and would try too hard to wear the fashion. Their musical taste would reach only as far as the most popular bands and would typically favour the bands biggest hits, and don't make efforts to seek out lesser known bands. They would usually wear Metal fashion but in the wrong combination, or clothing articles that had already fallen out of fashion, such as studded belts. They were the antithesis of a 'cool Metaller'.
Dave man?...he only listens to Metallica because they're popular....and the only band he's heard of...and that bullet belt he wears looks rediculous! What a Nugget!