humming a cheerful , if horribly out-of-tune rendition of rocking around the christmas tree to herself , mrs. henderson lurched to her feet , teetering like an awkward stork on top of her four-inch sparkly red cockroach killers , and then stepped over to the door , shoving the scarf she 'd just finished into a little blue gift bag which , by its crumpled appearance , had been passed back and forth between the residents many times .