When a person's body/brain goes into overdrive and continues to push forward without stopping until they are done. 1) Notorious among college students pulling all nighters and 2) partygoer's that are down to do anything.
1) I have a test that I have to study for and a project that is due tomorrow...time to enter fuck it mode.
2) Friend 1: Do you wanna do a line off that strippers ass?
Friend 2: Helllll yaaaa! I'm in fuck it mode let's go!
When someone gets pissed at the rest of the world because they decided not to finish what they started and then depreciate themselves by getting stuck in Fuck-it Mode.
Dude, why is Lori so butt sore? Don't mind her, she's lost in fuck-it mode.
Ruler of Lake Titicaca. Rumored to have a bunghole that gets very angry if it does not receive toilet paper. Cornholio the Great is often seen walking around with his shirt over his head and his hands in the air, chanting songs about his power, and his bunghole.
"I am Cornholio! You do not want to face the wrath of my bunghole, for I need TP!"
Butthead: Shut up, Beavis! (uh huh huh huh)
Beavis: Um, okay. (heh heh heh heh).