What will you call your mother's brother's brother-in-law?

As a whole I am both
safe and secure.

Behead me and I become
a place of meeting.

Behead me again and I am
the partner of ready.

Restore me, and I become
the domain of beasts.

What am I?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

What number when divided in half becomes zero?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

In two decks of cards, what is the least amount of cards you must take to be *guaranteed* at least one four-of-a-kind?

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.

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

Who has married many women but was never married?

Look at the picture and find out which square is not linked with any of the other squares.