Doc Louis is Little Mac's trainer in Nintendo's Punch-Out boxing series, which began in arcades in 1984 and reached wider fame on the NES in 1987. The line riffs on the famous Hulk warning, you wouldn't like me when I'm angry, recasting the usually supportive coach as the one about to snap. Shared as a short Discord and meme soundboard clip, it survives because the reference is instantly recognisable and the warning fits any moment where someone's patience is clearly running out.