tummy_fun wrote
I'd be afraid of rupturing the stomach. The expansion of the gas won't stop even if it's already too much for your stomach.
What about gulping down air and letting it out again after you've stretched enough? Good thing would be that you can stop whenever you want.
Stay carefully - life is fun but you only have one. No saving-points, no reset button.
You only have to worry about that if you can't belch, that is part of the reason for that mechanism/bodily function. As long as you can expell the gas when you begin to feel uncomfortable then it should be safe. That's not to say that I would suggest this method to anyone.
The best way to stretch your stomach to increase your capacity is to drink a lot of water and eat lots of breads.