It is a common trope in fiction, and in [good] SF particularly (and it's
even considered a good idea in real life, "ugly American" notwithstanding),
that when one is in "somebody else's" milieu, one should do one's best to
conform to the expectations of that milieu, or at least know enough to
avoid giving offense.

DGP's _World Builders' Handbook_ (WBH) provided some rules for generating
customs that PCs could theoretically run afoul of. However, rather than
asking people to pull out their PRNGs and copies of WBH, I'd rather ask
people to think about and list those kinds of 'things' that they've
encountered in real life, and maybe come up with a couple of variations on
them that could make life interesting for PCs.

NOTE: "R-rated" is specifically NOT excluded - I recall some examples in
fiction where starting from the assumption that if you stuck to what mom
taught you was decent/indecent, you couldn't go wrong, went wrong.

(Bonus points to anyone who can name the two references I was thinking of
when I wrote the subject line.)

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