Mat 12:41 The men of Nineveh shall rise in judgment with this generation, and shall condemn it: because they repented at the preaching of Jonas; and, behold, a greater than Jonas [is] here.

A better translation: The real men of Nineveh are raised up in comparison with this age to condemn it since those people reformed their ways after Jonah's proclamation and a greater herald is present here.

Jonah actually didn't preach to Nineveh. He announced that God would destroy them if they didn't reform. Jonah was personally dissappointed that Nineveh, Israel's enemy, listened to his warnings and changed their ways. Jonah was the herald, predicting God's wrath. Jonah was a flawed herald in the sense that he didn't want God to spare Nineveh even if they did reform. Jonah wanted God to judge people by who they were (enemies of Israel) rather than what they did (change their ways).

The normal translation makes Christ's statement seem metaphorical or maybe a prediction about the Last Judgment, but reading the Greek in context, Christ seems to be referring to his own previous two statements comparing Nineveh to the current generation. The key is an easy but incorrect translation of "raise up" as "rise up." Christ is raising the example of Nineveh. Nineveh isn't actually rising up. It is Christ's raising of the example of Nineveh that distinguishes them from the current generation.

"Men" is anêr, which in Greek indicates that manliness of "men," both for good and bad. It emphasizes the adultness of a man when compared to a youth or the mortality of a man when compared to the divinity of God. It is also used to mean "husband."

"Shall rise up" is from anistêmi, which means "to make to stand up," "to raise from the dead," "to rouse to action," and "to make people rise up." In the form used, it indicates causing these actions, "to raise from the dead" not "to rise from the dead (anistamai).'

"Judgment" is krisis, which means "separating," "distinguishing," and "judgment."

""Condem" is katakrinô, which means "to give a sentence against," and "to condemn."

"Repented" is metanoeô, which means "to perceive too late," "to change one's mind," and "to repent."

"Preaching" is kêrugma, which means "proclamation," "announcement," and "that which is proclaimed by a herald.

"Here" is hode, the demonstrative pronoun which means "this" in the sense of "what is present" and "what can be seen." With verbs of action and with a person (its use here), it means "here" as in "here I am" in the sense of "I am present."

"Greater" is pleiôn, which means "more," "greater than," and "further than."