AGK stands for Angry German Kid, the star of a series of mid-2000s YouTube videos showing a German teenager flying into violent tantrums while playing computer games, smashing his keyboard and screaming at the monitor. The clips became some of the earliest viral rage memes on YouTube, spawning endless parodies, remixes and subtitled parody rants. The scream itself is still used today because it distills internet rage into two seconds: everyone recognizes the sound of someone absolutely losing it, and editors drop it in whenever a moment needs maximum comedic meltdown energy.