Jimmy Fallon and President Donald J. Trump are officially in a 'Twitter feud'.
The two started the battle after President Donald Trump decided to criticize Jimmy telling him to "be a man"
Here's how Jimmy responded.
RAICES is a campaign to help stop border separation.
Apparently the fallout started two years ago when Fallon had President Trump as a guest on The Tonight Show during his presidential campaign and Jimmy messed with the President's hair to prove it was real.