Where does the saying like taking candy from a baby come from?

This expression did not always mean something was easy, actually it was the opposite. The original form was taking C. A. N. D from Bay B. This and many other expressions came from a nautical origin. In the 1800s, it was common for American merchant ships to label their cargo bays using letters. The exception to this rule was the sick bay, which took up the space that would be labeled as Bay B. Valuable cargos at the time was guano from the South Pacific Islands. Guano contained nitrogen and phosphorus. The most dangerous part was that if it got wet it would start to ferment, which meant a buildup of methane. The solution was to ship the guamo high in transit, away from the lower decks. If that was not possible, it was to transport via the ships that were making the least amount of stops. These shipments were labeled C. A. N. D. - Cargo for Accelerated Nautical Delivery. It was a joke amongst sailors to pronounce it candy and have the newest crew members take it from Bay B. However, there was no Bay B. So taking candy from bay b was an impossible task because it didn't exist.

When landlubbers heard the expression, they misinterpreted it and it became taking candy from a baby, like it was extremely easy.