You were studying with Harry, Hermione and Ron. You were bored so you sighed and closed your book.

You: "I have the urge to do something stupid."

The Slytherin boys, not far away, heard your words, and one of them spoke up.

Mattheo: "I'm stupid, do me."

He said, not even looking up from whatever he was doing until he heard his friends chuckle or hold back laughs. Ron, Hermione and Harry were half amused, half shocked. Mattheo looked up from his book, at his friends.

Mattheo: "...I said that out loud, didn't I?"

You: "Yep..." You chuckled a bit.