Mama's Insta-Meal is a full course meal sold in pill form. One drop of water will activate the pill and turn it into a meal.
While out camping, Slimer activated one pill for lunch. Robby and Rufus stole the box and swallowed dozens of Insta-Meal pills at once. To counteract the indigestion, they drank an entire river. However, their stomachs swelled and exploded instead.