B.K.
They do make and sell clips with elastic bands that you attach over the corners to go under the bed, but I'm not sure if they really work. I've seen them everywhere. Honestly though your best bet is to measure the debth of your bed and make sure that your next set of sheets have pockets deep enough...keep checking at Bed, Bath and Beyond for their clearance/sales I've had the best luck with great comfortable sheets that stay on my bed there. Have a great day.