What goes up but never comes down?

Can you place three balls such that the equation shown in the picture holds true?

The host of a game show offers the guest a choice of three doors. Behind one is an expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

Today is John's birthday.
A year ago, John had five candles and he lit all the candles except the one at the last.
Now he is going to light all the candles.

How old is John Today?

(He is not five today.....)

How can you leave a room with two legs and return with six legs?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

The more it dries, the wetter it becomes. Can you tell what it is?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

If a boy blows 18 bubbles,
Then pops 6 eats 7 and then
He pops 5 and blows 1.
How many are left?