Why do I need to know richard?

Because if someone calls you a gros richard, it's nice to know that they're neither calling your fat, nor did they forget your first name.

They are, however, not complementing you either.

What does it mean?

Un gros richard actually is an insult about people who are very rich.

Un richard is what you in English would call a ‘nob', ‘toff’ or (very) 'posh'.

Moreover, the term richard implies that the person in question doesn’t try and hide their wealth. 

It's an harsher insult than bourge (short for bourgeois). The French bourges can get away with being rich. They're the kind of rich that's (sort of) accepted as part of society. 

The gros richards, on the other hand, are the filthy rich who don't hide it. Think Bill Gates, but behaving like 50 cent. 

Just kidding, but there is a real – although subtle – difference there. A bourge is someone who can frame themselves as a leftie with socialist values (popularly called gauche caviar). A richard flaunts his money, bluntly and unapologetically – someone a bit bling.

Jouer le richard – playing Mr Fat Cat [not recommended in France].

Les cruises! C’est vraiment un truc pour les gros richards ça. – Cruises! That’s such a posh-people-thing.

Crache le morceau, gros richard. – Spill it, moneybags.

C’est qui ce gros richard dans le parking? – Who’s that fat cat in the parking lot?