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can't be serious

idiom

—used to express disbelief about what someone said
"I'm joining the army." "You can't be serious."

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can't believe
can't be serious
can't compete
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Cite this Entry

“Can't be serious.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/can%27t%20be%20serious. Accessed 29 Nov. 2025.

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