The "Hollywood" element of the term refers, naturally enough to the famous, celebrity studded, film capital of the world. When used in this context it implies a larger-then-life person, elements of bling or flashiness, moviestar good looks and of course a pearly white All-American smile.
The "Hopkins" element is less easy to pin-point, however it can most certainly be traced to Limerick, a city in the West of Ireland where a man by that name famously became the very embodyment of "Hollywood" style and glamour at the height of the Irish boom ecomomy. It is rumored that the person to whom the phrase became associated spent lavishly on dining out, local delicacies including Hot Chicken Rolls and ZeWeTon in particular, on cars and even Speed Boats.
A person who enjoys endulging in nightlife may also be know as a Hollywood Hopkins, especially if seen indulging in a lot of alcohol or practicing fashionable salsa dancing in nightclubs.
"I heard that guy Hollywood Hopkins once bought a round of 10 JaegerBombs."
"Did you hear about that guy that won all that money playing poker?
Yes I heard he was a real Hollywood Hopkins."