four-color glossies = F = fragile

frag n.,v.

[from Vietnam-era U.S. military slang via the games Doom and Quake] 1. To kill another player's avatar in a multiuser game. "I hold the office Quake record with 40 frags." 2. To completely ruin something. "Forget that power supply, the lightning strike fragged it. See also gib.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.