a bad leaf of spinach from a package of mixed greens, which may have a few telltale dark spots you would have noticed if you were paying closer attention but sneaks in as you tiredly throw a handful of the greens into the salad bowl after work and then when you're eating your salad you take the bite that has the bad leaf in it and are immediately struck by an overwhelming hit of vegetal decay, which overwhelms everything else and is still there after you swallow it, and the way that makes you suddenly grateful for all the other leaves in the bowl which have not yet gone bad