To tell someones to 'fuck off' or 'go away' hence 'fuck away'. Used by a group of people consisting of James Gary and Timo which tend to make up stupid things like that a lot
Bob: can i have a bite of your apple pie
Jim: no, fuck away bob, you cannot have a bite of my apple pie
When due to situational circumstances, or in respect to developing events, the outlook is bleak, expectations are dashed and/or an undesirable outcome is achieved.
You better get upstairs and turn off the oven if you don't want to fuck away a whole pan of brownies!