FGSFDS, (short for "For God Sake Fucking Die, Slacktard!") not to be confused with fagsfads, is the outcome of smashing your left fist against the keyboard. This is opposed to MNIJKL! which is when you use your right fist, FTYUGH! which is the outcome of using your forehead, and BHY! which is when you smack the keyboard with your Cock.
This originated on 4chan when someone replied to a random post with the extemporaneous text “fgsfds”, and through sheer dumb luck earned a GET. It was rapidly image macroed onto a picture of Wolf Blitzer. Since his upward pointing index finger was somehow salient to the /b/tards, the meme rapidly solidified into an index finger combined with the stupid text. Use of this in contexts outside a "fgsfds" post marathon thread usually indicates that the poster finds the thread’s contents ridiculous or otherwise nonsensical. It has become very old meme although it is sometimes used by fusty old /b/tards to indicate their superiority and obtain lulz at the expense of n00bs.