Take a picture of something, anything. It can be an animal, plant, mineral, what ever you want. Take several pictures of the item from extremely close up so it shows just
the color and the texture of the item. Then, in stages, take pictures of the same
image, just zooming out to full view. Send out the first text with the very first close-up picture. Give them a time in which to guess what the object is. Continue to send texts as you move outward from the object until someone guesses what the picture is of. Sort of like a slowly reversing zoom lens.
There are some camera phones that will allow you to take one picture and crop/edit to look like it is a zoom. If you have just such a camera then this will be easier and you might be able to use images you already have stored on your phone. If not, things with odd textures and colors work the best for that ah-ha moment.