New situation puzzles

At the end of the XIX century one american enterpreneur invented a system to withstand competition. This system we all use nowadays.

Why did a healthy young girl put a gypsum on her arm, which was not damaged?

The woman is speaking something and she is upset. Nobody can understand her but a man is filming her on camera. Why? And what is happening?

Why Alexander the Great told his army to shave off their beards?

When kids were watching TV, they were not frigthened so much. But when they saw others suffering, they realized that something was not right.

A man designed a device into which you can insert colored paper, and then get the ideal 100$. Experts can not distinguish them from the real ones. How does he do that, and why does he sell this device?

He died because he mixed up the colors.

Before going to bed, the woman hides her shoe in the safe. What for?

A man walks up to a cactus, looks at a piece of paper pinned there, and kills himself.

The man received the parcel in which he found a dead mouse. He reported this to the police, and the sender of this parcel was found guilty of fraud.

Following criminals’ trail, a police inspector entered a chess club. Assessing the situation, he told his assistants, “Detain those two!” How did he guess?

A person called the police and told them to ask about John K. Upon arrival at John’s house, the police found him dead. Examining the corpse, the police discovered severe injuries. But the apartment was in perfect order, without any signs of a struggle or break-in.