Lateral thinking is a term coined by Edward de Bono, a Maltese psychologist, physician, and writer. He defines it as a technique of problem solving by approaching problems indirectly at diverse angles instead of concentrating on one approach at length. Here are a few well-known examples of lateral thinking puzzles.

Lateral Thinking Puzzles

1. There is a man who lives on the top floor of a very tall building. Every day he gets the elevator down to the ground floor to leave the building to go to work. Upon returning from work though, he can only travel half way up in the lift and has to walk the rest of the way unless it's raining! Why? (This is probably the best known and most celebrated of all lateral thinking puzzles. It is a true classic. Although there are many possible solutions which fit the initial conditions, only the canonical answer is truly satisfying.)
2. A man and his son are in a car accident. The father dies on the scene, but the child is rushed to the hospital. When he arrives the surgeon says, "I can't operate on this boy, he is my son! " How can this be?
3. A man is wearing black. Black shoes, socks, trousers, jumper, gloves and balaclava. He is walking down a black street with all the street lamps off. A black car is coming towards him with its light off but somehow manages to stop in time. How did the driver see the man?
4. Why is it better to have round manhole covers than square ones? This is logical rather than lateral, but it is a good puzzle that can be solved by lateral thinking techniques. It is supposedly used by a very well-known software company as an interview question for prospective employees.
5. A man went to a party and drank some of the punch. He then left early. Everyone else at the party who drank the punch subsequently died of poisoning. Why did the man not die?

And my favourite logical puzzle:

6. Ten barrels are filled with apples. All but one of the barrels contain apples weighing four ounces each, but each of the apples in one of the barrels weighs five ounces.
   
   With one weighing, how can you determine which of the barrels contains the heavier apples? By one weighing, I mean that the scales are used only once. Yes, once.

For the answers, just ask nicely...