molly-guard
/mol'ee-gard/ [University of Illinois] A shield to prevent tripping of some Big Red Switch by clumsy or ignorant hands. Originally used of the plexiglass covers improvised for the BRS on an IBM 4341 after a programmer's toddler daughter (named Molly) frobbed it twice in one day. Later generalised to covers over stop/reset switches on disk drives and networking equipment.
[The Jargon File]