The gemara says that if the tochacha of yosef caused his brothers to be speechless, certainly the tochacha of hashem will do the same. Maharsha asks that we don't find that Yosef gave tochacha to his brothers? See Beis Haleivi on parshas vayigash that Yosef's comment "is my father still alive" is the greatest tochacha possible bec. it proved that their entire story was based on falsehood and lies. Similarly on the yom hadin even for things where we seem to have good excuses and a plausible story, Hashem will show the underlying contradictions in our actions - AYEIN SHAM.