Usually a USC film student or a postal worker, more commonly known as "McBitch" or a "Johnny" (reference to the phrase: Johnny come lately). A McNally will always hate the Dave Matthews Band (not without good reason), steal sunglasses from his favorite band (The Secret Machines), and be born in Brooklyn (New York). Plus he's had anal sex.
McNally: "Hey guys check out these new _______!"
Anyone else: "Dood, I got those like a month ago you fucking Johnny"