a couple

Question: There is a couple that is always together. They go anywhere they want to go. They can't be separated. No one can touch them. They are the size of a ping pong ball. What is it?

Question: Where do all the letters sleep?

Question: What tastes better than it smells?

Question: What goes in the water black and comes out red?

Question: What two things can you never eat for breakfast?

Question: What asks but never answers?