A Wild Hare (1940)
Elmer Fudd: [first occurence of this line] Be vewy, vewy qwiet. I'm hunting wabbits.
[first occurrence of this line]
Bugs Bunny: Eh, what's up, Doc?
Bugs Bunny: [with his hands over Elmer's eyes] Guess who?
Elmer Fudd: Heddy Wamarr?
Bugs Bunny: No.
Elmer Fudd: Cawole Wombard?
Bugs Bunny: Nope.
Elmer Fudd: Wosemawy Wane?
Bugs Bunny: Nope. Guess again.
Elmer Fudd: Owivia De Haviwand?
Bugs Bunny: Nope, but you're getting warmer.
Elmer Fudd: Say, you wouldn't be that scwewy wabbit, would you?
Bugs Bunny: Ehh... could be!