You show your young audience a prop which you call ' Bunny' s Magic Castle.' This castle consists of a brick wall with a door on the left and on the right.
The children see how the bunny runs to the other side as soon as the door is closed. If you open the door again, of course the bunny is gone. Before opening the door on this other side, the bunny rabbit runs back to its original place, which the magician can't see.
This carries on as long as you want it to. The kids will be screaming with pleasure, as they always know where the bunny is, while you, the magician, keep looking in the wrong place.
In between times the cheeky little bunny peeps out from behind the brick wall, only to disappear immediately after, but suddenly turning up again in a completely different place.