Sally's 'clubhouse' is really just a few of those little tables for children and (as LJ so lovingly calls it) The World's Greatest Pillow Fort, and nobody is going to disagree, since nobody else has seen it, since Sally won't let you in without the password. She keeps a bunch of colouring books and markers there, along with a snack stash she's managed to keep a secret from Slendy. Naturally, her snacks come from LJ, who's the only one who knows the password.