Tribal Knowledge: Good Writers Borrow…

I’d be interested to learn of any methods that GMs use to “borrow” elements from another setting without making it obvious to players that they’re doing so (especially if the players are likely to have exposure to that setting).  Do they simply rename an element?  Do they tweak something important (trivial?) to obfuscate the source?  What tips can you provide to keep those elements — particularly the changes — handy during play, so they don’t get forgotten or lost in a bunch of other notes?

–Bothered by the Business of Bigger, Better “Borrowing”