For example, take this classic:
A man lives on the eleventh floor of an apartment building. To go to work, he takes the elevator all the way down to the ground floor. Upon coming home from work, he takes the elevator to the fifth floor, then takes the stairs the rest of the way. The only time he doesn't do this, is if there is someone else in the elevator with him, or if it is raining. Answer? The man is short-statured, and without the aid of another, or an umbrella, cannot reach the 11th button of the elevator.
This is unsettling for a number of reasons.
Number 1, we automatically assume that the man in question is able-bodied, and anything which disproves conclusions we make by revealing the fallacy of our assumptions is unsettling.
Number 2, why does this guy live on the eleventh floor anyway? Did he inherit his apartment? He surely would not have chosen to buy it, given the difficulty he encounters using the elevators.
Have a look at another puzzle.
George and Susan are found dead in a room, surrounded by broken glass. However, there are no marks or injuries on their bodies, and an close study of the bodies reveals nothing to suggest they've been poisoned. How did they die?
The answer? George and Susan are goldfish. The fishbowl fell off a table and shattered, causing their suffocation.
Again, unsettling, notwithstanding the death in this puzzle.
Firstly, we assumed that George and Susan were humans. Again, with the fallacy of our assumptions being revealed to us, the entire lateral-thinking exercise becomes something of a nightmare. Who names their goldfish "George" and "Susan" anyway? Why not "Nemo" or "Dory" or "Goldie" or "Sushi"?
Secondly, why was nobody in the house alerted by the sound of breaking glass? Surely someone would have heard, and come to the aid of the poor defenseless goldfish. Unless they did arrive on scene, only to find that it was too late. Which is a possibility. However, another possibility is that the house is completely empty at the time. Which raises the question - how did the goldfish bowl fall off the table in the first place? (a perfectly un-scary answer to this is that there is a cat, and the cat knocked it over... but then wouldn't the cat have then eaten the dying fish?!)
And another puzzle:
The police receive an anonymous tip-off regarding a serial murderer on the loose. They have only two pieces of information: his name is John (last name unknown) and he is currently at a certain address. When the police raid the address, they find a mechanic, a plumber, a truck driver and a carpenter playing poker. Without any communication, they immediately arrest the plumber. How do they know they have the right man?
And no, these people are not wearing name tags on their uniforms.
Answer? The plumber is the only male in the room. The mechanic, truck driver and carpenter are all female, and thus unlikely to be named John.
Well the only unsettling thing about this is that we assumed they were all male. Honestly, what's a woman doing, being a mechanic or a carpenter? Go back to the kitchen.
Ready for another one?
A man and his wife are speeding towards the hospital in their car. The car breaks down, so the man leaves, locks the car, then runs to the nearest building for help. When he returns to the car, his wife is dead, and there is a stranger in the car. Explain.Again, the unnecessary death in this puzzle is unsettling, but only the least of our worries. There is a STRANGER in the car! Is it some crazy psycho murderer who broke in with a coat hanger? How did he kill the wife?
Answer: they were speeding to the hospital as the wife had gone into labour. While the husband was away from the car, the wife gave birth, but unfortunately died of blood loss. The stranger in the car is the baby.
Now all kinds of unsettling things come into play! Firstly, this poor guy has to clean all that blood off his car seats. Secondly, his wife is dead, and he's probably not very happy about that either. Thirdly, now he's a single father. What will he do with the baby? How will he feed it? Will he have to remarry? Fourthly, the baby too is probably going to die unless this man hurries the f*** up and gets them to the hospital for some medical attention. Fifthly... imagine referring to your own baby as a stranger.
So the moral of this story is: always take your car in for regular servicing.
And a final, somewhat gratuitous lateral thinking puzzle:
A man is found hanging from a noose in the middle of a large barn, locked from the inside. His feet are hanging several feet from the ground, but there is no furniture in the barn he could have stood upon to reach the noose. There is a small puddle of water below him. How did he manage to hang himself?
So everyone has heard this one. He climbed upon a massive icecube, and waited for it to melt. I heard this first in primary school, and could not sleep for several nights after it.
From where did he procure this giant icecube? This would've taken a lot of planning! Does he have an industrial-sized freezer? Is there a business which supplies massive chunks of ice (and if there is, do they realise that their product killed this man, and probably killed a lot of other men, who tried to emulate this first man?)
Also, death by hanging is caused not necessarily by strangulation, but by a sharp breaking of the spine at the neck. When someone hangs, after having a trapdoor beneath them removed, or having kicked a chair from underneath them, the sharp fall will (hopefully) break the neck, resulting in a somewhat faster death than the death this guy suffered, waiting patiently for this ice to melt.
It sounds like some diabolical trap from the Saw movie franchise. Oh wait, it is.