Greg is trying to explain to his girlfriend that he has a good reason for missing their dinner date; however she was not having it . So he threw up his hands uttered fuck it as he walked away.
1. When you dont want to sit there looking at two (or more) options like an idiot, and choose to do the thing you originally thought of.
2. When youre not sure whether or not you should do something, and decide just to do it (also see yolo)
1. Im going towatch a movie! But what about a game? Nah, fuck it, i'll watch the movie
2. Should i go to that party but not train for my exam? Fuck it, i'll just go to the party