That's just good advice. Unless you are a snake, of course. It is said that a snake can eat an item so large in relation to its own head that it would be the equivalent of a human swallowing a watermelon whole -- and without using his hands. Anacondas, among the world's largest snakes (a record-breaker was 28 feet long and 44 inches around), are said to be able to consume an adult human being!
Just about everybody on this planet seems to believe that snakes can unhinge their top and bottom jaws -- this is not true. The remarkable thing about the snake jaw is that the two halves of the lower jaw are not connected at the front. This allows them to swing away from one another and to work independently to pull food into the muscular throat. Besides the wide-opening jaws, snakes have a hard-cased skull in order to prevent brain damage from large thrashing animals clasped in their jaws. And perhaps most importantly, considering how long it takes to swallow a huge, mouth-filling living thing, they are able to shunt their respiratory tube to the side so they can still breathe, even with a chicken egg lodged in their throat.
See snakes of North America.