As coined by Australian comedian Hannah Gadsby. Hungry Clackers describes the way pants will ride up into your crotch while walking if you have large thighs that rub together.
'Clackers' is a pleasant reference to the external female genitalia. The 'hungry' part is referring to the way it kinda seems like the crotch is trying to stuff as much of the pants into itself as it can. This is not dissimilar to how one would shove a large amount of food into their mouth when hungry.
"While i enjoy the idea of a stroll along the beach, I am afraid my hungry clackers are making the reality of a long walk quite unpleasant".
"woah check out my hungry clackers; my regular length pants just became 3/4 pants"