How to avoid holiday snacking?

So I have lost about 50lbs so far... (down to 190 from 240).

I do everything right. I lift 3x a week, I run twice a week. I stick to a high protein diet, with lots of veggies thrown in.

My one problem: When I visit my parents, my diet goes to shit. The house is filled with booze and chocolate, and they constantly offer me junk. (For example, got me a chocolate orange for Christmas among other stuff)

Back at grad school, I eliminated snacking by simply not keeping snacks in the house.

And it works. When in the past I'd have ate a bunch of cookies or some other crap, I eat a carrot or make some herbal tea.

But now, I'm stuck in suburbia for a week and find myself constantly shoveling junk in my face. Anyone have any suggestions for dealing with the temptations of an unhealthy household over the holidays?