Pretty self-explanatory. But just in case you need a description a fucko is some stupid person who pisses you off cause he's an idiotic prick, who rarely if ever uses his head. Stay away from fuckos, they usually end up hurting you.
A jackass, dumbshit sort of person, who although tries to be smart about things ends up with their head up their ass.
In Goodfellas DeNiro's character (Jimmy) refers to a couple of feds sleeping in their car as Fucko's. As he taps on the glass to wake them (they have been tailing him) he says: "c'mon fucko's lets go for a ride."
When a person makes a mistake, does or says somethingsomething stupid, or does not know what they are talking about. Normally used in sarcastic context.