The words resonated with all the churlish power of a sulking child and probably would have sent most people away, half-justifying their action with the thought that it was what she'd asked and half-annoyed they'd gone to the trouble to come over only to be yelled at through the door.  Draco had known Pansy since they'd been stealing cakes, however, and claiming to have no idea what had happened, so he just pulled out his wand, cast alohomora, and let himself in, Hermione at his heels.