Good Riddles

Question: How can forty elephants have forty-fore heads?

Question: I am the only organ that named myself.What am I?

Question: When do you go at red, but stop at green?

Question: 100 feet in the air, yet its back is on the ground.

What is it?

Question: I'm red, blue, purple and green.
No one can reach me, not even the queen.

What am I?