Good Riddles

Question: Two men went into a restaurant. They sat at a table and the waiter came by and asked, "What do you want to drink?"

The first man said, "I'll have H₂0."

The second man said, "I'll have H₂0 too."

The second man died.

Why?

Question: I met a man on a bridge he tipped his hat and drew his cane in this riddle I said his name. What is his name?

Question: What has no beginning, end, or middle?

Question: Draw, fire, or fill me;
I'm still empty.

What am I?

Question: what did the postman say to the mailbox?