No U is a way to reverse the action that somebody has done to you are said to you. Kinda like a Uno Reverse card?
Kate the thot said “I’m blocking you on my contacts!!”, so I said “No U”
The only comeback for the famous 'Ur mum gay lol'
Timmy: 'Ur mum gay'
Gary: 'No u'
Timmy: *Combusts into flames and falls to the depths of Hell where he will never see the light of day again*
A comeback in case of the worst of the worst insults
Jeff: Tyrone stop leaving the kids
Tyrone: STFU ur mom gay lol
Jeff: No u
Tyrone: has a aneurysm and gets raped by 20 black Colonel Sanders
Sanders: Butthole Licking Good
The ultimate comeback to a twelve year old on Fortnite calling your mom gay.
12 yr old: you're mom gay lol
Me: no u