Redditor verantgoten took what he thought was just a cute picture of the place his 3-year-old son chose for hide-and-seek. I case you don't see it, the child is behind the mirror. At first glance, the optical illusion is that verantgoten, in the mirror, has feet below the mirror. Look again. When you look at the picture closely, it appears that the feet are not attached to any human legs at all!
Weird, huh? See, the boy is wearing pants that are not quite the same shade as the wall, but are the exact shade of the shadow on the wall. You can enlarge the picture even more here, if you need to.