The sound comes from Pluto's Kid Brother, a Disney Pluto cartoon released on April 12, 1946, where Pluto deals with his mischievous younger brother K.B. Clips from these wartime era shorts later circulated widely online as short reaction audio, prized for their clean, expressive acting without dialogue. This panting and wow moment survived because it condenses a whole cartoon gag into about six seconds. Editors still reuse it for pet content and nostalgic animation edits where an old fashioned sense of wonder fits better than a modern voice clip.