Take this medication 'on an empty stomach'. [=when your stomach is empty because you have not eaten for a time]
When I had the flu, just the thought of eating made me 'sick to my stomach'. [='nauseous']
She felt a flutter in 'the pit of her stomach' when he walked through the door.
(..) He is coming to me in chains. - If anyone should be afraid, it's... - You. Don't even think about it. I hope this turns out better than your plan to cook rice in your stomach by eating it raw and then drinking boiling water. This plan's nothing like that plan. - How? (..)2011 Kung Fu Panda 2