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うそでしょ uso desho
No way. Tell me that's not true.
What does uso desho mean?
Literally that's a lie, right — but nobody is being called a liar. It is pure disbelief, and it works equally for a cancelled train and a friend's sudden good news.
Example
え、もう終電?うそでしょ。
Wait, that's the last train already? You're kidding.
Vibe
Who you can say this to, and how it lands.
Safe to use Fine in ordinary conversation.
The story behind uso desho
The grammar is doing the softening. 嘘 alone is a flat accusation, but the tag でしょ turns it into an appeal: please tell me the world is not like this. That is why the phrase can be shouted at a departures board without anybody taking offence.
It is one of the most transferable reactions in Japanese, because it fits both directions of shock. Bad news gets it, and so does a friend announcing they got the job. Regional and personal variants are half the fun: うそやん in Kansai, うそだろ in a blunter register, and a bare 嘘 said very quietly when the news is genuinely too big.