Funny Riddles

Question: What does a man do only once in his lifetime, but women do once a year after they are 29?

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

Question: I have all of your knowledge but could fit in your hands.

What am I?

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 a word made up of 4 letters, yet is also made up of 3. Sometimes is written with 9 letters, and then with 4. Rarely consists of 6, and never is written with 5.