Only use this phrase as a last resort option, even against the deadliest of foes. There is no coming back from this one. Once said, the damage will be reversed and your opponent's beliefs are destroyed.
A: Ur mom.
B: no u
A: *ruptures his appendix and fucking dies*
Hurts the opponent's mental health with raw emotonal damage. Can be reversed with "No u".
A: Fuck you bitch.
B: Ur mom gay
A: *had a stroke and fucking died*