Well, you certainly seem professional.
2 seconds sound clip from Scooby-Doo, Where Are You! - The Backstage Rag (S1E9).
You can hear this line at 00:07:12.915 in the Blu-ray version of the episode.
Quote context
[...]
- We would like to inquire about arranging an audition for our trained dog.
- He's a great talent. Do a bit, Scooby.
- Well, that was pretty good. What do you say, Johnny?
- No. Sorry, chum, but you can't work this show unless you're a puppet.
- You're very good. Are you a puppet master?
- Oh, my, no. I just fiddle with them as a hobby.
- Well, you certainly seem professional.
- Well, why not? The great Pietro has helped me.
- Yeah, what's with you, Scooby Doo?
- A witch? I get it. One of the puppets scared you. OK. Let me up.
- That's OK. I'll go put Johnny away.
[...]