Acronym for "Fresh and Full of Life", a catchphrase gleaned from Mentos commercials, which in the late 90s was sarcastically trumpeted by sardonic slackers in IRC and MUD/MOOs.
Mentos and Mentos related topics were popularised by the band the Foo Fighters, who spoofed their shmaltsy advertisements in a video. Unfortunately, this backfired on the Foo Fighters when they became constantly pelted with tubes of Mentos during their live performances.