Let's have a guide on how to answer behavioral questions. 1. Why do you want to work here? (Eg: why do you want to work for Facebook?) 2. How did you resolve conflicts with a teammate? Edit : 3. How do you efficiently manage time/work with teams that are in a different time zone? Add more questions/answers to this thread. We can have a common place to look it up.
1. You tell why you want to work there. 2. Tell how you resolved a conflict with your team mate. It's best to be honest with such questions rather than trying to game them. You don't want to end up in an environment where you are miserable because you don't fit there. It's still important to prepare for the questions because you want to articulate yourself properly. But be honest.
I don't think being very honest helps here. If you tell them that it is your dream to work at Facebook/Google, the interviewer wouldn't be impressed. They know that's true but they still expect to come up with a story. I would tell them that they're still scaling and additing a lot of users/customer base. I would like to solve scalability challenges and help build large scale distributed systems (that's my experience). I don't know if this a right answer or should I change it to something else.
You could spend some time introspecting why that is your dream. Maybe because you actually want to solve scalability challenges? In that case say that. I gave an answer that didn't mention scalability, billion users, impact or social. And I got through FB's process.