"F.C.P.S.I.T.S.G.E.P.G.E.P.G.E.P." has the speculated meanings:
The widespread opinion  is that "F.C.P.S.I.T.S.G.E.P.G.E.P.G.E.P." stands for one of:
"Fuck Condoms, Premarital Sex Is The Shit! Get 'Em/E'r Pregnant, Get 'Em/'Er Pregnant, Get 'Em/'Er Pregnant!"
According to the guitarist's personal LiveJournal account, the song name matches exactly with a personal saying as described above.
According to the band's FAQ, "No comment, and even if you figure it out, it doesn't mean anything." (Presumably, the title is a joke that does not mean anything related to the lyrics or the song's meaning itself.).