The phrase carries a heavy dose of internet nostalgia, but for mobile users, it’s a name that still sparks a bit of anxiety. Originally a flashing, singing browser prank from the early 2000s, this "virus" has evolved into various mobile iterations that range from harmless jokes to genuine malware.
Look for any apps you didn't download or those installed right before the "virus" appeared.
Android: Hold the Power button, then long-press "Power Off" until the "Safe Mode" prompt appears.