what to get your girlfriend's parents for christmas

Well, that's a tricky one. I'd say it depends on what they're like. If they're the type of people who love fancy things, maybe some nice jewelry or a bottle of expensive wine. But if they're more down-to-earth, something simple like a home-cooked meal or a gift certificate to their favorite restaurant would be perfect. Either way, make sure you put a lot of thought into it and let your love for your girlfriend shine through. Good luck!