Well, Scooby-dee-Doo.
2 seconds sound clip from Scooby-Doo, Where Are You! - Hassle in the Castle (S1E3).
You can hear this line at 00:21:01.363 in the Blu-ray version of the episode.
Quote context
[...]
- I must admit, Mr. Bluestone, you're a good magician, but a bad phantom.
- Man, I wonder if, like, there really is a treasure.
- Hey. That's Scooby barking. Come on!
- Look! Scooby found something.
- Scooby Dooby Doo, where are you? We got some work to do now.
- Scooby Dooby Doo, where are you? We need some help from you now.
- You know, we got a mystery to solve, so, Scooby Doo, be ready for your act. Don't hold back.
- And, Scooby Doo, if you come through, you're gonna have yourself a Scooby Snack. That's a fact
[...]