Computer crashed and the file wasn't saved — GG (we're toast).
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culture
Imported from English 'GG (good game)' via early-2000s StarCraft and CounterStrike scenes. In Chinese the original courteous sense ('well played') has largely shifted to 'we lost' / 'it's over' — closer to RIP. To say 'gg ez' (good game easy) Chinese players still use the English.
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Very casual / internet slang. Spoken as 'jee-jee' (English letters) or just typed in chat. 完蛋了 (wándàn le, 'doomed') and 寄了 (jì le, 'sent / cooked') are Chinese-native equivalents in current slang.