What Am I Riddles

what am I? (medium)

Question: Lose me once, and i’ll come back stronger Lose me twice, and i’m gone forever What am I?

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?

Lemon spy (medium)

By jena

Question: What is square and green?