When a person or thing does something that is extremelyefficient 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
A military slang used in the Unites States Army that describes a team of soldiers, usually in a maintenance unit, who repair and inspect sensitive electronic equipment, including, but not limitted to, such things as missile guidance systems.
"That iffie shop is squared away! Now, I know how things work in an iffie, so I won't go down there, but you tell them that first sergeant is happy."