Here is a really cool little mental puzzle that's well worth trying out on your family and friends. So choose your victim and tell them you're going to prove that you can read their mind. Here's how it goes.
1) Think of a number between 1 and 10.
2) Multiply it by 9.
3) Add those two digits together so that you end up with a 1-digit number. (And whichever number they chose, the sum will add up to 9. That's because the sum total of anything that's multiplied by 9 will add up to 9. Think about it, 9, 18, 27, 36, 45 etc.)
4) Now subtract 5 from this number. (Of course they will end up with the number 4)
5) Work out the corresponding letter that matches this digit. For example, 1 would be A, 2 would be B and so on. (So naturally your victim will end up with D)
6) Now think of a country that begins with this letter. (Denmark is usually the first country that springs to mind because countries beginning with D are pretty sparse.)
7) Now think of a mammal whose name begins with the second letter of this country. (The second letter in Denmark is E, so normally, "elephant" will automatically be chosen.)
8) Think of the most popular color of this animal. (Normally, people will decide that elephants are grey.)
9) Tell your victim, "YOU'RE THINKING OF A GREY ELEPHANT FROM DENMARK!"
This works like a charm in most households. But I've got to warn you, it's not totally foolproof. Some clever individuals may choose another country beginning with D, like Dalmatia. Then, when the big announcement is made, "You're thinking of a grey elephant from Denmark," they say, "No, I'm not. I'm thinking of a black ape in Dalmatia!" Otherwise, it works over 90% of the time with everyone else.