YOU SAID:
That is the single most stupid thing I've ever heard.
INTO JAPANESE
それは私が今までに聞いたことがある最も愚かなことです。
BACK INTO ENGLISH
That's the most foolish thing I've ever heard.
INTO JAPANESE
それは私が今まで聞いた中で最も愚かなことです。
BACK INTO ENGLISH
That is the most foolish thing I've ever heard.
INTO JAPANESE
それは私が今まで聞いた中で最も愚かなことです。
BACK INTO ENGLISH
That is the most foolish thing I've ever heard.
That didn't even make that much sense in English.