No u is the most effective and most common comeback in case of an insult.
It is basically a reverse card from Uno; every negative comment someone made on you or your family, it can be turned back on him with these two simple, but nonetheless powerful words, defeating your opponent with his own words.
No u is so powerful, that if the dragons in Skyrim knew about it, Alduin would have certainly defeated the Dragonborn in the final battle.
– Ur mum gai.
– No u.
The origin of the phrase apparently is found on the forums of Something Awful, where users liked to get into meaningless and trivial arguments, and after a while everyone was aching to show the hypocrisy of the insulters, thus creating a weapon, they can use against them…
That is on the internet, though I think almost every kindergartener knows this ultimate comeback and none of them would hesitate in the heat of an argument to drop this verbal warhead.
The term is one, that is or was present in all our lives at least at some point.
No u is still enjoying great popularity, and it doesn’t look like it’s going to change.