a Mac-user who is obnoxious and arrogant. They are identified by those Mac-users who insist on showing off their latest iPhone, iPad, etc. all the while incessantly bragging about Mac in an arrogant and holier-than-thou manner.
These people often drive Priuses, wear uber-nerdy close on purpose, hang out in coffee shops just to be seen, tell you how much they 'care' about the latest human rights/animal rights craze (Japan, Haiti, etc.) and always offer their unwelcome, obnoxious opinion no matter what. These tools are walking Mac commercials.
at the scene of a car accident
Mac fag: "Hey, I took some pictures of the crash."
Level-headed person: "Thanks, man, that's helpful."
Mac fag: "Check it out, if you do this with your finger you can zoom in for more detail and did you know that my iPhone 4 can even *blah blah blah* five minutes later
You know the Snow Leopard OS doesn't have all the virus and security problems that a PC *blah blah blah*...
Level-headed person: "Dude, seriously. You're such a mac fag. It's really not a good time, and my PC is just fine. Stop preaching at me. There are more important things to worry about...like this fucking car accident you caused."
Mac fag: "I get way more miles to the gallon with my hybrid and did you know that I can check traffic on my iPho-- *punch*
Everyone else at the scene of the accident: *applause*