The term LIKE OLD LETTUCE can be summarized by the word 'LIMP', which is a four-letter word. LIMP is an adjective that describes something that is not firm or rigid, but rather soft and drooping. It is often used to describe vegetables, such as lettuce, that have gone bad and become wilted. In this case, LIKE OLD LETTUCE is referring to something that is not firm or rigid, but rather soft and drooping, like old lettuce.