What is both possible and impossible at the same time?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

A man dies of old age on his 25 birthday. How is this possible?

You have a 12 liters jug full of water. You have two empty 8 liters and 5 liters jug. How can you divide the water into two equal parts using these jugs?

The Puzzle: A girl, a boy, and a dog start walking down a road.

They start at the same time, from the same point, in the same direction.

The boy walks at 5 km/h, the girl at 6 km/h.

The dog runs from boy to girl and back again with a constant speed of 10 km/h. The dog does not slow down on the turn.
How far does the dog travel in 1 hour?

I had an infinite supply of water and 5 litres and 3 litres jars.

How would you measure exactly 4 litres in the least number of steps?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

A man was going to bleach his socks because they had gotten muddy the day before. As he was pouring the bleach into the washing machine, he spilt some on the floor. He got some cleaning fluid and mopped it up with a rag. Minutes later he was dead. What killed him?

Can you find out the total number of triangles in the given figure?

The dirtier I get, the whiter I look. Who am I?