I always thought the funniest joke in the Torah is coming right up in Vayera --- starting at Bereishit 19:30, with the punchline at verses 37-38. It seems to me that the story of Lot and his daughters was obviously a (pretty nasty and sick, actually) national joke for Israel/Judah, at the Ammonites' and Moabites' expense. Sure, we're all descendents of Terah, but YOU'RE ALL MAMZERS! Nice way to describe the origins of your neighbors...anotherfrom the Mouth of G-d by the hand of Moshe! ...a good reason later on for Ammon and Moab to be tribute-paying subservient peoples, forbidden in the Temple in Devarim 23:4.