Samuel was out for a walk when it started to rain. He did not have an umbrella and he wasn't wearing a hat. His clothes were soaked, yet not a single hair on his head got wet. How could this happen?

What is always in front of you but can’t be seen?

What goes up but never comes down?

When can we add 2 to 11 and get 1 as the correct answer?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

Our product and our sum always give the same answer. Who are we?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Can you figure out the logic I used to decide the order of the following words:
gun, shoe, spree, door, hive, kicks, heaven, gate, line, den

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

It has five wheels, though often think four, You cannot use it without that one more, You can put things in it, you can strap things on top, You can't find it in the market, but you can still go shop. What is it?