system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: What causes that feeling in your stomach when you drive quickly over a steep bridge / go down a steep drop on a roller coaster?
gpt
It's literally your stomach moving up in your torso. Our organs aren't rigidly held in place; they're more floating in your torso, anchored by ligaments here and there. Usually you don't notice it, but a sharp change like what you describe can cause perceptible movement.