Hogfather

87

Old IBM mainframes (as well as, later, the first IBM PCs), had large, bright red, power switches, causing the phrase “big red switch” (often abbreviated as BRS) to enter the hacker’s jargon.

Hex, after seeing Death enter the laboratory, is in fact asking if Death has come for him, which (a) throws an interesting light on Hex’s own feelings about his sentience, and (b) explains why Death’s reply to Hex starts with the word “No”.