The sound comes from Pixar's Finding Nemo, released in 2003, where a flock of seagulls perched near Sydney Harbour keeps shouting mine as they eye up food and anything else they can claim. The moment became a shorthand for selfishness, and clips of the chant spread through reaction videos, edits and soundboards as an instant joke about grabbing something first. It still works because the joke needs no setup, the voices are instantly recognisable, and greed over something small is easy to parody in almost any video.