"Read this quickly as there isn't much time. This is for your eyes only. Know that the whole world around you is an illusion, a fake. Know that everything you see, feel, hear, taste, or smell is just an illusion. Everything you know is a lie. But know that you aren't alone, and there are others that watch you, and care for you. There are also those that right now are watching with evil intent. Go now and burn this letter, as it is evidence of a glitch, and probably the last one you shall ever see. You must completely destroy it. I feel better knowing that you now know the truth, and shall see the world for what it really is.
P.S.- Work quickly and don't act suspicious, bad things are working swiftly against you right now as you read this. Don't show or tell anyone about this letter."
I would write the letter in very fancy writing, put it in an envelope, write READ ME on the front, and wax stamp the envelope closed, using a very strange insignia. I would probably put this in the mail pile of someone I know. I think it could cause some brix shitting.