fat electrons = F = faulty

fat-finger vt.

1. To introduce a typo while editing in such a way that the resulting manglification of a configuration file does something useless, damaging, or wildly unexpected. "NSI fat-fingered their DNS zone file and took half the net down again." 2. More generally, any typo that produces dramatically bad results.

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