The phrase became a staple meme sound in the late 2010s as short chase clips spread across Vine, Instagram and later TikTok. Its power comes from the two-step delivery, starting almost conversational before exploding into a shout that can caption almost any flight, from cartoon chases to real pets and toddlers. Because the question needs no setup, editors reuse it as a universal fleeing joke, and the split spelling why are u running keeps it searchable as both a reaction clip and a standalone soundboard button.