Metal Sonic is the robotic counterpart of Sonic the Hedgehog, first introduced in Sonic CD in 1993 as a mechanical copy built to match Sonic's speed. In later games and animations he is often shown as cold, calculating and impatient, which makes short dismissive lines from him popular for edits and reaction videos. The you're getting annoying clip is shared in that spirit, used to shut down a noisy opponent or an irritating moment without a long argument. Its appeal comes from the contrast between the calm delivery and the blunt insult.