Considering I can eat two and still feel empty I reckon 10 is easy. Might reduce my life expectancy by 25% though
I doubt 10 would be that hard to most people. (on a proper empty stomach you an hear rumbling)
I think the problem would be the amount of liquids you would need for all the bun and then it would swell up in your stomach and make you feel fuller I guess?
Maybe the key would be to eat them slowly so you don't get the dry mouth