In case you are wondering, this post is not a prank itself. But I acknowledge that it sounds exactly like one.
I think I invented this practical joke but you'll let me know if you have heard anything like it. It's very, very cool. Seriously, it will blow your mind.
The Set Up
Select a victim who is likely to believe the incredible bullshit that follows. It works well with kids because they can't yet distinguish science from magic. But it's fun for anyone with a sense of humor, especially the gullible ones.
It helps to have an accomplice who can nod and agree with the story you are about to tell, as if it had been in the news recently and all well-informed people know it.
Your story to the victim is that scientists discovered that mirrors made from certain types of sand don't merely reflect light; sometimes they act as a window into a dimension that is similar but slightly different from our own. The most fascinating part is that the scientists devised a simple way to tell if your mirror is normal or a window to another dimension. Next. . .
1. Find a full-length mirror. Ask your victim to stand in front of it, about a foot away.
2. Explain that you will ask the victim to do three different motions in front of the mirror. If the mirror does everything the victim is doing, it is just an ordinary mirror. But if any of the three motions are not duplicated in the mirror, what you are seeing is a similar but slightly different dimension.
3. Ask the victim to keep his feet planted and turn at the waist - left, then right, then back. Note aloud that the mirror did exactly the same.
4. Ask the victim to keep his body still except for shaking his head back and forth as if saying "no." Note aloud that the mirror did exactly the same.
5. Speculate that this might be an ordinary mirror, but there is one more test to be sure.
6. Ask the victim to put his nose about an inch from the mirror and keep his entire body still except for moving his eyes rapidly left-right-left several times in a row. Now ask the victim if his eyes in the mirror appear to be moving similarly.
Here's the freaky cool part. The victim will see his eyes in the mirror appearing to stare straight ahead, unmoving, while in fact they are vigorously moving back and forth. This is an illusion, obviously, but it is so unexpected that the victim will be surprised.
The victim's first reaction will be that he is seeing something impossible. That's when you jump in with your explanation of the window to another dimension. Your accomplice should be nodding and confirming the story.
I've tried it a few times and it's a lot of fun. Let me know if it works for you.