1. You are in a house where all four walls face south. A bear walks past the window. What colour is it?

White, because it's a polar bear. Is this because it's on the very top of the earth (North Pole), so all four walls would automatically face south, or something?

2. A woman has five children, and exactly half of them are boys. How is this possible?

They're all boys, so half that, quarter it, do what you like; they're still boys. Alternatively, you could say 'half of them' would include the mother, so therefore she has three sons (3), two daughters (2) and herself (1), which equals six. Half of six is three, and that's how many sons she has.

3. Take one from 19 to leave 20

I haven't figured this one out...

4. What would you add to nine to make six?

180 Degrees? A mirror? Minus three (as in, 9 + -3 = 6)? I'm not sure.

5. There are two sheep standing in a field. One is facing north and the other south. How can they see each other without turning round?

One sheep is called north, the other is called south? Wait... they'd be looking at each other anyway.

6. What question can you never answer yes to, even though it's true? (there is more than one, but they have the same gist)

"Can you tell me a lie?"

7. What question must you always answer yes to?

"Can you say yes?"

8. If a group of people contain a father, a mother, a son, a daughter, an uncle, an aunt, a sister, a brother, a niece, a nephew and two cousins, what is the smallest number they can be?

Two: the father and mother are cousins, and the father can also be an uncle, brother, newphew, etc...

Those were cool, I probably got a few wrong.