[coined in response to WYSIWYG] Describes the command-oriented ed/vi/nroff/TeX style of word processing or other user interface, the opposite of WYSIWYG. Stands for “You asked for it, you got it”, because what you actually asked for is often not apparent until long after it is too late to do anything about it. Used to denote perversity (“Real Programmers use YAFIYGI tools...and like it!”) or, less often, a necessary tradeoff (“Only a YAFIYGI tool can have full programmable flexibility in its interface.”).
This precise sense of “You asked for it, you got it” seems to have first appeared in Ed Post's classic parody Real Programmers don't use Pascal (see Real Programmers); the acronym is a more recent invention.