Good Riddles

Question: You're stuck in a room with no way out, no windows, no doors, and no roof. All you've got is an apple and a knife. How do you get out?

Question: An item looks square from outside, Circle when opened and Triangle when taken out.

Question: Two cops walk into a doughnut shop. One gets a sprinkle doughnut and the second one gets a sugar doughnut. What did the third cop get?

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: I don't like crackers and I don't drink tea. I just want to eat what I used to be.