expression
God only knows what may happen; who knows what will happen
Proverb expressing uncertainty about an unpredictable outcome, often with a sense of suspense or anxiety. Literally 'whether a demon appears or a snake appears'.
結果はまだわからない。鬼が出るか蛇が出るかだ。
We still don't know the result. God only knows what may happen.
この勝負、鬼が出るか蛇が出るか、最後まで目が離せない。
This match could go either way; you can't take your eyes off it until the very end.
Also means 'God only knows', but is a more direct translation and less idiomatic than 鬼が出るか蛇が出るか, which carries a traditional Japanese flavor.
A traditional Japanese proverb. The exact origin is uncertain, but it likely stems from the idea that both demons (oni) and snakes (ja) are unpredictable and potentially dangerous, symbolizing an uncertain outcome.