Somebody who is entirely self absorbed and won't do anything for anybody else. Also Sombody who drops another person in the shit.
"dude you just told my wife i'm having an affair, you jack bastard!"
Where one of your mates or work collegues has a "Jack Bastard Attitude", or where they act like a jack bastard continuously with the same attitude towards you.
"cor blimey Dave has a bit of a jackitude today."
