You are stood between two people who are either good friends, or in a relationship. In this instance it is a man and woman who are married.

The man is given a business card and asked to think of any two digit number and to secretly write it on the business card, but not to show anyone.

His wife also has a business card containing around forty numbers written on the back. She is asked to select any four of the numbers and add them up, silently.

On the click of your fingers both parties will name the number he and she is thinking of.

A few moments pass.

You click your fingers.

Man and Wife both shout out \ "eighty three \" at the same time!

Both are utterly shocked beyond speech.

Not only that, but as a meaningful keepsake the man can keep his card, and the woman can keeps hers.

But is it a mystical connection, or a sharing of their psychologies!

Not a bad effect for two business cards and a marker pen.