When a person or thing does something that is extremely efficient and/or Powerful
Or something that is generally Gil approved:
EG: Machine-Gunning, Being not gay, Helicoptering, Being generally Indestructable
Also see : Gil Approved
1. "I have engineered the hell out of this computer to the point that it has become Gil-Iffic"
Person: I have murdered nick, twisted off his head, and then raped his mother
Gil: Maximum Gil-Iffic