This stands for 'shut the fuck up you fucking piece of shit'.
Most people use this word when they are angry or annoyed.
Girl: Omg, Stacy is having an awesome party tomorrow!!!! You have to come!!! There are going to be a lot of really cute guys there and a lot of food and we are all going to play spin the bottle and get locked up in a closet with the other person for 10 minutes!!!! Omg..... <Other girl interrupts her>
Girl #2: OMFG!!!!! JUST STFUYFPOS!!!!!! DAMN! YOU ARE SOOOOOO FUCKING ANNOYING!
by MAMA123 June 5, 2010
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