Believe it or not, crackers stay incredibly crisp in the freezer because the air is very dry.
Preheat to 300°F (150°C). Spread crackers on a baking sheet in a single layer. Bake for 3–5 minutes. This evaporates the absorbed moisture and "re-sets" the crispness.
Crushed crackers hold moisture better than standard breadcrumbs in meatloaf or meatballs.
Key difference : Tough = hard/difficult to break. Stale = soft/not crisp.