This is one of the few things I've ever performed that came to me in the spur of the moment and I was able to execute it in the moment as well. There was no planning involved, but I was only able to accomplish it due to a very specific circumstance.
I was meeting up with a potential collaborator on something that is non-magic related. We were having coffee at a place near my apartment. She was slightly older than me, in her mid-40s, and worked in publishing. As the conversation evolved from the subject we were originally there to talk about, she began telling me about her house in the Hamptons that she had does redone with her husband. They were putting the finishing touches on it right now like choosing the lighting, the window treatments, some final painting options, etc. I told her that sounded like a lot of work for a big house. I had just redone the lighting in my apartment and even that was a lot of effort.
As we continued to talk she began asking me what other types of projects I'm involved with and I mentioned that often I use my background in magic when working on a project. She seemed very intrigued by this and asked to see something. The coffee shop we were at had decks of cards and other objects that would have lent themselves to being used in a magic trick, but I was struck with inspiration and I took the box of crayons and a sheet of paper from the stack of stuff they had set aside for kids who came in with their parents. (This is near Park Slope, Brooklyn, an area famous for people lugging their kids around while they get their expensive coffees or buy yoga-pants.)
I drew four squares on the paper, with the second one being smaller than the others. Then I took an orange crayon and printed the word "BLUE" at the top of the page. I told her to take any four different colored crayons out of the box and then color in each of the squares one of those colors. She had a free choice of any crayons and a free choice of which color she would use for which square. I then gave her the black crayon and told her to scribble over one of the squares she had already colored in. She scribbled over the third square which she had originally colored red with the black crayon.
We were left with the image below. I told her to hold onto that drawing for now.
We stopped by my apartment and before we went in I asked her to take out the picture we made at the coffee shop. "You may wonder what this is," I said. "It may seem like some psychological test to see what colors you would choose. [The project I'm working on with her has its roots in psychology.] You might think there was a psychological reason I made the one square smaller or that I printed the word Blue at the top but I did it with an orange crayon. And you might think that I could tell something about you by which color choices you made, and then which square you chose to black out. But this isn't psychology at all. It's all very straightforward. I printed the word Blue at the top, because that's what this is, a blueprint. This is my apartment. On the left is my kitchen, the small square is my bathroom, the next square is my living room, followed by my bedroom. Remember when I said I just changed the lighting in my apartment?"
I gave her my key and had her go inside. The lights were on in the kitchen, glowing purple. The bathroom was lit up with yellow light. The lights in the living room were off. And blue light was shining from the bedroom. When I flipped on the living room lights, everything was bathed in a deep red glow.
The method here will be obvious to some of you, but other people are completely oblivious to it. I knew after talking to this woman, her relationship with technology was not one where she would be familiar with what was going on behind the scenes.
The method is that my apartment is completely decked out in Philips Hue lights, these lightbulbs can pretty much emit any type of light you want and they are controlled with your phone. Below is a video of the lamp on my nightstand going from a standard lightbulb, to fluorescent, to red, blue, and finally purple.
It takes under 20 seconds to set the lights via an app on my phone. So in the process of checking a text after leaving the coffee shop, I set all the lights in my apartment to match her drawing. Presto.
These lightbulbs are pretty cool. They can be pretty much any color, they can mimic any type of lighting (halogen, skylight, antique, etc.), they can flicker like candles, they can be set to go off like lightning, they can synchronize to whatever music you play. You can have it so they emit a very natural light and if you have multiple bulbs set-up you can set it so it will appear as if clouds are passing in front of the sun. What I mean is that intermittently the lights will dim in sequence as if something is traveling across the sky blocking out the sun. There are dozens of apps you can buy to do different things with them. You can have it so any time you start a movie the lights dim to a particular "theater" setting automatically. You can really set them to do anything you want. If you wanted all of the lights in your house to glow blood red whenever you said, "I am Satan, Lord of the underworld," you could do that.
I use them frequently in the context of other tricks, but this was the first time I used them as a secret method. I doubt I'll use them again like that, but who knows. One of the things I'll do with these lights is give my spectator the four aces and ask her to separate the reds from the blacks without looking at the faces. I'll have her try it over and over, in different colored lights, until she gets it right. If she gets it right under blue light I'll say, "Hmm, yeah, this is probably around the same color as your aura. So in this light you'll have a hypersensitivity and you'll be able to do all sorts of seemingly extra-sensory things." To "prove" this I'll perform OOTW for her under the same colored light and then show her that she separated the entire deck perfectly. "You should really buy some blue lightbulbs," I say. "Obviously it's a color that makes you extra perceptive and usually that brings about increased creativity and concentration as well." I'll take any chance I can get to spout nonsense in a very rational way.
Another thing you can do with these lights is set them to glow in any color that you pull from any picture on your phone. For example, I will sometimes take a picture of the person I'm performing for and then set the lights in my living room so one light is the color of her lips, one the color of her eyes, one the color of her hair, and the other color of her flesh. I haven't found a great rationale for doing this, but people find it interesting to be in a room that's illuminated in the colors of their own body. And you can certainly come up with some bogus reason for why this helps you reach into their mind, or fool their eyes, or whatever.
The bad news is the lightbulbs are like $60 a pop, so if you want to deck out your whole home and you have a wife you have to justify your purchases to, you're screwed.