Look! A secret passage!
2 seconds sound clip from Scooby-Doo, Where Are You! - A Clue for Scooby Doo (S1E2).
You can hear this line at 00:17:12.974 in the Blu-ray version of the episode.
Quote context
[...]
- I'd like to get a close look at that ghost.
- But his trail's not. Look. Glowing footprints. Now all we got to do is follow them.
- The footprints vanish right into the side of the cliff.
- You're right! Shaggy, you're a genius!
- I am?
- Sure. Who else but you could have sat down on the rock that opened the secret passage?
- I thought that rock was pretty suspicious.
- Come on, gang. Let's go inside.
- Wow! Wowee! We're in a giant underground cavern!
[...]