Funny Riddles

Question: Why can't the Tyrannosaurus rex clap?

Question: Timmy's mother has three children. The first was named April. The next was named May.

What is the final one's name?

Question: When you do not know what I am, then I am something. But when you know what I am, then I am nothing. What am I?

Question: What is the only question you can't answer yes to?

Question: How can "L" be greater in size than "XL"?