Mike, Bert and others in “Mike's Whistle”

If engines can't whistle properly, they shouldn't try.

Then why do you?

I was talking about Duck! Unlike him, I've an excellent whistle.

[laughs] If I had a whistle like yours, Mike…

Yes…?

...I'd lose it.

What?! Whistles are important, Rex! Engines without whistles aren't proper engines at all.