Looks like Shaggy wants to try for the Ape Man role in the picture.
3 seconds sound clip from Scooby-Doo, Where Are You! - Never Ape an Ape Man (S1E7).
You can hear this line at 00:20:29.045 in the Blu-ray version of the episode.
Quote context
[...]
- It sure was clever of him to lock himself in that trunk yesterday.
- And tell that phony story about the Ape Man throwing him in there.
- Well, I can't thank you kids enough.
- Shaggy should get most of the credit. Where is Shaggy?
- Looks like Shaggy wants to try for the Ape Man role in the picture.
- But there's Scooby Doo in the other chair.
- Surprise! It's the Scooby head the Ape Man was wearing.
- We sure fooled them, Scooby. We ought to be in the movies.
- Yeah! Scooby Dooby Doo! Hee hee hee!
- Time to go, gang. It's getting dark.
[...]