It's no one we know, but whoever it is, I'd like to ask him a few questions.
4 seconds sound clip from Scooby-Doo, Where Are You! - Foul Play in Funland (S1E8).
You can hear this line at 00:06:02.189 in the Blu-ray version of the episode.
Quote context
[...]
- What do you say? Let's go find the others.
- I don't see Scooby or Shaggy anywhere.
- There's someone going along behind that fence.
- It's no one we know, but whoever it is, I'd like to ask him a few questions.
- He's taking a ride on the Ferris wheel.
- It stopped. That man is trapped up on top.
- You've turned it all the way around, but he's gone.
- But he couldn't have climbed down without us seeing him.
[...]