Good Riddles

Question: When I come in, someone else leaves, I know everyone, yet no one knows me. I'll meet you all only once in your life, Causing mayhem and mischief and sorrowful strife. What am I?

Question: What is square and green?

Question: What do you call an angry pea?

Question: Why did the hen cross the road?

Question: What do you call two banana peels?