You only use the living room when the other members of your household are out. You know you're an extreme introvert when you don't even use the kitchen or bathroom until nobody is around. You're probably very territorial about your bedroom.
Your friend pays you a visit and ends up being entertained by your flatmates because you're hiding out.
The idea of throwing a party at your house horrifies you purely because it's at your house, therefore you can't leave and go home.