Boy, it was a neat setup. He and his gang were switching their fake pieces of art for the real ones in the museum.
5 seconds sound clip from Scooby-Doo, Where Are You! - What a Night for a Knight (S1E1).
You can hear this line at 00:19:44.752 in the Blu-ray version of the episode.
Quote context
[...]
- Yikes!
- We did it, Scooby-Doo. We did it.
- It's the curator, Mr. Wickles.
- We've got to hand it to you kids. We never would have suspected Wickles as the art swindler.
- And they made the fakes at night in a secret workshop behind the mummy case.
- Oh, my gosh, Professor Hyde White!
- It's Scooby-Doo with a shoe.
[...]