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Meaning

Ripple Man is the final boss from a horror game played by Bilibili UP主 "逍遥散人." Since Sanren is afraid of horror games, that livestream night had constant problems (Steam crashed, Bilibili upload failed, Mahjong Soul gacha was terrible, browser crashed, lost Minesweeper on the final 50/50). So people say "Ripple Man has arrived" when things go wrong.