(Flashback to little Sam and Dean…)
Sam Winchester: Are monsters real?
Dean Winchester: What? You’re crazy.
Sam Winchester: Tell me.
Dean Winchester: I swear, if you ever tell dad I told you any of this, I will end you.
Sam Winchester: Promise.
Dean Winchester: First thing you have to know is we have the coolest dad in the world. He’s a superhero.
Sam Winchester: He is?
Dean Winchester: Yeah. Monsters are real. Dad fights them. He’s fighting them right now.
Sam Winchester: But dad said the monsters under my bed weren’t real.
Dean Winchester: That’s because he’d already checked under there.
From Supernatural – Season 3 Episode 8: ‘A Very Supernatural Christmas’ (3×08) | Produced by The CW