Alex (after he opens the door and catches Mer and Der having sex on the stairs, his hands immediatly cover his eyes, and Mer runs up the stairs and Derek covers himself with a shirt): Whoa.
Izzie: Oh my god, Derek!
Derek: Hey, Hi!
Alex: Dude, get a room!
Izzie: On the stairs? Doesn't that hurt?
Meredith (giggles): Leave us alone, we're newlyweds.
Izzie: A post-it wedding does not make you newlyweds.
Derek: You know what... you're newlyweds too. (throws keys at Alex) You need your own space.
Alex: Dude, what are these?
Derek: Key's to my trailer, your new home. Enjoy.