Quote Originally Posted by it-ogo
По-моему, это просто иронический отсыл к манере когда-либо голодавших людей при любых непонятных или тревожных событиях на всякий случай запасать еду в больших количествах.
I'd say a more appropriate saying in that case would be: "Запасаться солью и спичками." The phrase: "Сушить сухари" is used exclusively as a metaphor for the preparation to jail as in the USSR you were allowed to take a very limited number of items (one small suitcase) when arrested. The standard content was: rusk, tobacco packs (махорка), tea packs, and some warm clothes. Some (usually a half) was to be immediately contributed to the "common saving trust" (общак) upon arrival and the rest kept for himself (even if you don't smoke and sincerely hate tea). The rusk was to be eaten by the inmate himself until he gets used to the food served in jail. The tea was used as a light narcotics and could save the inmate in times of trouble (exchanged for some services or protection) as much as tobacco.