this is the wrong way of saying it... as the correct pronunciation is "f'sho". there are stupid white trash and preppy ppl that like to try and act cool so they say it "fo sho" trying to be ghetto... which sounds so stupid as ur not supposed to make the "fo" sound and instead a short "fi".
snoop: yo nigga wuddup wit dat trippy ass joint you just fed me playa?!
em: ay man dis shits purple haze dawg, im feeln it already!
50: f'sho nigga!