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Stands for "Freezing Index Finger Syndrome" Usually occurs around October when the weather becomes colder. Inflicted by constantly playing handheld videogames where your index finger is alone and cold.
Person 1: "Dude, what's wrong with your finger?"

Person 2: "I couldn't stop playing Birth By Sleep last night, and now I have FIF Syndrome!"
by Keria1010 October 03, 2010