I posted this one somewhere else here, but it's fun...

Two people are in on this - the Physic and the assistant.
You place 9 hard back books on the floor in rows of 3 books. Then send the physic out of the room and have a guest pick (point to) one of the books. Call the physic back into the room...Here's the trick to it. The assistant points to each book in turn and when the chosen book is pointed to the physic announces that's the book...They can tell because the assistant is using a pointer/stick to point to each book and to the position of the book in the rows of 3...say it's the bottom right book that was picked. The assistant, while pointing to each book is always pointing to the bottom right corner of each book...that is how the physic knows. See how long it takes people to figure out the trick...it's a lot of fun.

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Spectorized