Head MotherFucker In Charge, the work equivilent of Big Man On Campus. The person who actually gets stuff done. Not necessarily the CEO or Chairman of the Board, but definitley high up in the business. It's a good idea not to piss off the HMFIC.

i was first introduced to this term by my boss. He introduced me to the head of the Southern Nuclear Comission (responsible for all the nuclear reactors in the southeastern US).

boss: "Ted, this is J--- M---------, Southern Nuclear HMFIC."
me: "Nice to meet you, Mr. M---------."

try to be nice to the HMFIC. Otherwise, he might say AMF and your business will be SOL.