Whatdja do is the compressed, spoken form of what did you do, and the clip circulates online as a user shared reaction sound rather than a widely credited line from a named film or show. Its exact original recording is not well documented, so its life is mainly on soundboards and in short video edits. The phrase works because everyone recognises the tone from real life, the moment someone discovers damage or mischief. That familiarity keeps it reusable across gaming clips, pet videos, pranks and everyday fail compilations.