In which Looney Tunes short did Bugs Bunny first say 'What's up, doc?'?

Bugs Bunny first said “What’s up, doc?” in the Looney Tunes short A Wild Hare.

Directed by Tex Avery and released on July 27, 1940, A Wild Hare is widely regarded as Bugs Bunny’s first official appearance. It also presents the rabbit with the familiar design, personality, and voice style that became standard, opposite Elmer Fudd as the hunter. The short’s relaxed greeting became an instant signature because Bugs delivers it while acting completely unconcerned in the face of danger.

Tex Avery later explained that “What’s up, doc?” was a common expression in Texas, where he grew up, and that he did not initially consider it especially significant. The line became iconic after audiences responded strongly to it in theaters. Porky’s Hare Hunt (1938) is sometimes mistakenly cited because it features an early rabbit prototype, but that character was not yet the fully established Bugs Bunny. A Wild Hare was originally released as a Merrie Melodies short and was later reissued as The Wild Hare.