Well; it's a new hip word with the youngens these days. It just means "that's how i feel right now" or "extremely relatable". They use it primarily when that is the heaviest emotion in their life at that point in time.
by Jim Noobert June 13, 2018

Originated from Danish, but the internet being the internet changed the meaning. (Originally this meant to be even cited or happy), to now be slang for something entirely else, often being the polar opposite of happy.
Original use:
Tom: Hey Tim are you in a big mood today!?
Tim *excited*: Yes Tom, I am!!
Current Internet use:
Tim: I’m dead inside man
Tom: Big Mood
Tom: Hey Tim are you in a big mood today!?
Tim *excited*: Yes Tom, I am!!
Current Internet use:
Tim: I’m dead inside man
Tom: Big Mood
by hedgelinghog July 14, 2018

big moose 1: did you see what our moose daddy kenny tweeted?
big moose 2: about how hot josh dun is? big boy meese mood
big moose 2: about how hot josh dun is? big boy meese mood
by kennys.big.moose.2 September 4, 2018

by Steamyd January 15, 2020

by OiBruvAmmaSheepFamInnit?.co.uk March 13, 2020
