Guess a magic number. This is a simple trick where you ask a person to perform some easy math that leads him to the same answer almost every time. This is what you should tell the audience member:
Think of any number.
Multiply it by 2.
Add 8 to the total.
Divide it by 2.
Subtract your original number from the total.
Remember this new number--it's your secret number!
Count on the alphabet until you get to the letter that goes with your secret number. (Number 1 is A, Number 2 is B, and so on.)
Think of a European country that goes with that letter.
Go over to the next letter of the alphabet.
Think of a large animal that begins with that letter.
Once the audience member has thought of it, just say, "I know what you're thinking of...the number 4...and an elephant in Denmark!" This will work every time.