Dangling a reward in front of their noses (but just out of reach) will keep them going forever. You can use a carrot, a cauliflower, a potato, an pointless job, a minor raise, a broken laptop, your old GSM, some beads and mirrors or just about anything you find in your desk drawer. You can use the same reward over and over again or for more than one of them at the same time: no matter how hard they try, they'll never get it!

(Toon Boot)