The Brief: "I am screaming" is a hyperbolic way of expressing one's shock or amusement.

DEEP DIVE
Similar to I’m shook, I’m dead, I literally can’t even, or ROTFL,ย “I am screaming” is a way of indicating that something is so striking, that it’s scream-worthy. It is a way of showing extreme reactions including surprise, amazement, and amusement. The phrase can also be used more dryly and sarcastically like in the damn bro you got the whole squad laughing meme.
Last New Years my ex n I broke up bc we got in an argument after going out andโ the photos app made this movie of the night and I am screaming this is so rude and funny of Apple pic.twitter.com/U7jCie4wJz
— grace (@guhhrace) January 7, 2020
MARK REUNITED WITH LUCAS AND TEN I AM SCREAMING FIRST SUPERM SELFIE OF 2020 pic.twitter.com/p10raNiqvW
— Bey ๐ (@eribomb_) January 6, 2020
This girl brought her cow๐๐ yโall Iโm screaming!๐๐๐#TheBachelor
— T (@viva_coloniaa) January 7, 2020