Your stomach is technically not inside you.
Your digestive tract is really just a long tube with two openings that lead to the outside (the mouth and, ahem, the anus). You don’t have to dissect any bodily tissues to get to food digesting inside your stomach or intestines. If you image yourself to be a kind of huge, biological donut, your digestive tract is analogous to the donut’s hole - it is inside the donut in a way, but it’s not really “inside” the donut. Therefore your stomach is technically on the outside of your body.
Yeah. Anatomical philosophy.