when you're either sad or angry at yourself or someone else
'' how're you feeling homie ''
'' I'm fucked up so leave me alone''
He/she thought that he/she was gonna fuck him up and make him go crazy, not knowing that the guy was fucked up long before them, and would be fucked up after they were gone, if it didn't kill him.
Fucking up something in the process of fucking something up.
A man fucked up when he went to rob a bank, but FUCKED UP when he forgot his guns.