When it comes to your campaign, if you come across something you like — an idea, a character from a novel you’re reading, a cool scene from a movie — steal it and use it in your game. Period.
There is absolutely no reason to be bashful about shamelessly borrowing and stealing elements from any source under the sun. If you like it and you think your players will like it, make it your own. This process is fun, saves you prep time and can lead your game in unexpected directions.
There are no legal pitfalls here (you’re stealing ideas for your personal game, not plagiarizing for a published product), but there are a few things to watch out for:
Han Solo is already taken: Modeling an NPC on a fictional character is great. Using that famous character’s name is lame. (Putting Han in your Star Wars game is a whole different ball of wax, of course.) Ditto with Gandalf: Name an NPC Gandalf, and your campaign takes a turn for the humorous or boring.
It has to fit your game: Sometimes you’ll stumble across something so awesome that you want to jam it into your campaign even though it doesn’t really fit. I’d err on the side of being incautious with this one — if it’s cool, try to find a way to make it fit — but there are times when no matter what you do, the thing you yoinked just feels wrong.
Change at least one thing: Sometimes all you need to change is the setting, and suddenly the plot of Blade Runner looks nothing like the movie to your players. Other times, as with Walt’s Star Wars campaign that used the plots of the movies, you don’t even have to change that. But you have to change something.
Trust your instincts: Whatever first excited you about the idea you’re stealing is the one thing you absolutely shouldn’t change about it.
Are you a shameless kleptomaniac when it comes to your campaigns? Has it ever backfired on you?