[Avodah] reactionary takanos and gezeiros

[Sholom Simon via Avodah]

Many times throughout history, the g'dolei hador make takanos or 
gezeiros in order to distinguish ourselves from other groups (often, 
from Jewish breakaway groups).

Probably the most famous one is to eat hot food on shabbos (to 
distinguish ourselves from tzadukim).  Another (lesser known one): 
the prohibition to have non-Jews play music at a simcha.  (IIRC, the 
S"A specifically allows it, and that Jews used to get married on 
Friday afternoons, combine it with a shabbos meal, and the band would 
play into the evening. After Reform used this "loophole" to permit 
organ playing at services, the g'dolei hador made a gezeira prohibiting it.)

My question is this:

I will be in a kiruv situation, and this subject will come up (as we 
are going to have a cholent on shabbos).  I would like to draw some 
sort of analogy between these rabbinical ordinances as reaction and 
something comparable in secular life.

Can anybody thing of a secular (ideally, American) law or common 
custom/practice that is done in order to distinguish ourselves from 
some other group/idealogy?

(E.g., a swastika, or something like it, appears as an ancient design 
in many other cultures -- but nobody would use it nowadays because of 
it's Nazi association.  But I'm looking for a better and more 
relevant example (because in American, before the 1930's, that wasn't 
a common design anyway)).

-- Sholom