I first heard it in the context of an old TRS-80 program called ZAP, which stood for Zaftig Alteration Program. This allowed you to go into any file (including executable programs) and change things down at the byte level - sort of like an interactive version of the Unix 'od' utility. I've seen the term used only a few times outside that context, but only a few times in a non-parenthetical context.

k