What does this rebus mean?

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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 the last thing you take off before bed?

A thief enters a store and threatens the clerk, forcing her to open the safe. The clerk says, “The code for the safe is different every day, and if you hurt me you’ll never get the code.” But the thief manages to guess the code on his own. How did he do it?

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

You need to complete the maze by entering from the entrance marked below in the figure near the yellow circle, bottom left and leaving from the exit point near the green circle, bottom middle.

Rule of Game: You can move only by exchanging green and yellow circles.

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?