The red door.

Amy stepped through the red door, into darkness. She gulped. She could be absolutely anywhere, for all she knew. In the caves of Mars, the dawn of time, the heart of a dying star... where could it possibly be as completely dark as this? She couldn't see a thing. The ground was strangely soft under her bare feet. Almost like... carpet?

The lights clicked on.

"SURPRISE!"

There was the Doctor, and Rory, and all her friends, and several dozen people she didn't recognise, including a few aliens with tentacles for faces, all standing in her living room around a huge pile of presents and a gigantic strawberry-iced cake. "Happy birthday!" crowed the Doctor, as everyone else fell silent, their mouths hanging open in astonishment as Amy stood before all of them with no clothes on. "It is your birthday, isn't it? I can never quite remember how years work. Say, why don't you have any clothes?"

Amy shrieked and spun around, intending to flee. The door behind her was locked, of course. She turned and bolted for the closest available exit, which happened to be the front door of her house. On the way there she tripped on a present and landed with a splat in the enormous cake, covering herself with cream and icing. Rory was the first to start laughing, and then everyone else joined in.

Amy threw open the front door and ran out into the street, naked and sticky with cake, mortified beyond belief and thinking of nothing but how to get herself away from everyone as quickly as possible. It wasn't until the door shut behind her, and the lock clicked, that standing naked on a public street was just as embarrassing as standing naked in front of all your friends in the privacy of your own home. By that time, it was too late.