After all, Mr. Frere, I'm a ventriloquist myself, you know...
3 seconds sound clip from the Dead of Night (1945) movie soundboard.
You can hear this line at 01:21:19.692 in the Blu-ray version of the movie.
Quote context
[...]
- Come in! Glad to see you, Sylvester.
- Mix yourself a drink and let's get down to business, eh?
- Well, thanks, brother. I will.
- But suppose you tell me, where I can find Mr. Frere. I guess he can't be very far away.
- Well, er I rather thought I had an invite from our young friend here.
- After all, Mr. Frere, I'm a ventriloquist myself, you know...
- There's a clean towel in here.
- Thanks.
- Sorry, but I can't bear anyone touching him.
- Oh, that's all right. Forget it.
- Say, I sure like to know how you pulled that gag.
- What gag? 'Cause I don't quite follow you.
- Well, just now before you came in.
- You know, for a moment, I could've sworn it was the dummy speaking. And me a pro.
[...]

 Dead of Night (1945)
 Dead of Night (1945)  Phantom of the Opera (1943)
 Phantom of the Opera (1943)  Scooby-Doo, Where Are You! (1969)
 Scooby-Doo, Where Are You! (1969)  Halloween III: Season of the Witch (1982)
 Halloween III: Season of the Witch (1982)  Knight Rider (1982)
 Knight Rider (1982)