The current GURPS rules for Savoir-Faire require a separate skill for each context the skill is used. While each skill is only ME it is neither representative or reality or fun for the player to have to fork over 2 points to get "Savoir-Faire (Dojo)" at IQ +1. Instead, the following rules are proposed.
Savoir-Faire (fill in the blank) defaults to Savoir-Faire -2 and is modified by a relevant skill according to the following scale (defaults count):
1-4 -3 5-6 -2 7-8 -1 9-11 - 12-13 +1 14-15 +2 16-17 +3 18-19 +4 20+ +5
Some examples of the relevant skills are SF (Religious), Theology; SF (Gun Club), Guns OR Armoury; SF (Dojo) Karate OR Judo; SF (Theater!) Acting OR Performance OR Directing; SF (Business) Merchant. Players could make a case for SF (Underworld) modified by Streetwise, but chances are simply using Streetwise will be more advantageous. However, in certain instances, SF (Underworld) would be more appropriate than Streetwise (i.e. the Yakuza fancy dress ball).