ROTFLYSHSTBISNL Share definition Flag Rolling On The Floor Lauhing Yet Some How Still Typing Because I'm Secretly Not Laughing... Guy 1: Dude my mom just got water ballooned!!!Guy 2: ROTFLYSHSTBISNLGuy 1: ... ROTFLYSHSTBISNL by datswagerman August 27, 2013 Get the ROTFLYSHSTBISNL mug.