Good Riddles

Question: what do you call a pair of pairs?

Question: A horse jumps over a castle and lands on a man, then the man disappears. How was this possible?

Question: An old man wanted to leave all of his money to one of his three sons, but he didn't know which one he should give it to. He gave each of them a few coins and told them to buy something that would be able to fill their living room. The first man bought straws, but there was not enough to fill the room. The second bought some sticks, but they still did not fill the room. The third man bought two things that filled the room, so he obtained his father's fortune. What were the two things that the man bought?

Question: What room can no one enter?

Question: There are 5 frogs, 1 die. How many left?