We play hide and seek almost every day. I love to challenge them. I bring them into the kitchen, and tell them to 'sit-stay'. I show them the toy that I'm holding. I then go into the other room and hide the toy - either under the couch cushions, behind the desk, under a pillow, etc.
They wait patiently until I say "Go get it!", and then they charge inside and overturn everything until they find it. We do this several times each day, and they have a ball!