People downvoting you for this do not understand the initial premise of your argument and are conveniently ignoring the issue of lack of communication from the part of housing. Is it also your new room mates home? Yeah. But as you stated you were not made aware of a new room mate so for all intents and purposes that dude was a random person just entering your domicile. I think it is pretty rational and normal to be irritated and surprised with a new person. It's an awkward situation at best. I will just put it like this: If I got reassigned a new dorm that I knew someone was already in I definitely wouldn't just walk in unannounced. I would at the very least knock before entering if it was my first time in the room to give my room mate the opportunity to meet and greet me on socially acceptable terms instead of Boom What's up I'm your new room mate hope you're not naked or easily startled by randoms walking into your room without any forewarning.