I actually have some personal experience with this. And it's not pretty, so if you don't want to hear about this, don't read on.
Right before I entered into binge eating disorder treatment, I went on a massive bender and was consuming 10,000+ calories a day for 5 days. My body couldn't store that much energy, so I ended up "only" gaining 3 pounds. If I stored every extra calorie, I would have gained 10 pounds in less than a week.
The body will eliminate a portion of the extra calories through waste (TMI, I know). I had extremely high blood sugar during that time and I am certain I was urinating sugar. (Yikes!) Also, I think my metabolism became very fast to deal with all that food.
No, you won't gain 30 pounds by eating 175 pints of ice cream, but you might perforate your stomach, go into diabetic shock, and likely die. But you won't look fat by doing so. Bloated yes, fat no.
So, kids, don't try this at home.
[And just so that you know, I went into treatment April 2008 and am doing much better]