Savoir-Faire: By gamers, for gaming

On page 218 of GURPS 4th Edition Basic Set: Characters (Jackson, Pulver, Punch, 2004), Savoir-Faire is defined:

This is the skill of appropriate behavior in a subculture that has an established code of conduct -- for instance, high society or the military.  When dealing with that social group, a successful skill roll lets you interact without embarrassing yourself, detect pretenders to high standing, and so on.

It's a skill that requires specialization for the particular subculture; it can include anything from basic etiquette to dressing guidelines and even special symbolic meanings for tiny gestures or ways of standing.  There can be times when the proper behavior choice according to savoir-faire is to be rude, or dress like a colorblind nitwit, or support the campaign antagonist; for a fairly cheap skill (in terms of character points), savoir-faire can play a HUGE part in the overall story.

That makes things awfully jarring when, as a player, I have no idea what my character ought to be doing -- and the most I can do is rely on a bare roll of the dice, and hope the GM can turn this into a decent part of the story.  To make the roleplay work more smoothly, I've been researching the anecdotal notes of various subcultures:  if we start a campaign in any setting next month, I want to be part of the story, not a mechanic with a character sheet and a few six-siders.

( I can't say there's any such thing as  )