Why don't you have them bob for apples in a (dollar store) swimming pool filled with rats (fake of course). Order some gum eyeballs from oriental.com. They have a lot of stuff that you can buy, a dozen rats for like $4.00 and they have spiders, too. Remember the episode when they put the tarantulas on a person's head? You can inexpensively and creatively mimic this with a cardboard box and blindfolding them, then place fake spiders on their heads. Let their imagination take over and do the rest from that. Also, you can have them to drink milk with worm ice cubes (gummy worms in ice tray. Just think of creative, safe ways to have fun.