> I didn't know whether to believe him or not until I got glasses and found that they don't make reflections on the eyeball side.

They do when the light is just right. You're telling me you wear glasses and you've never seen a reflection of your eye and back toward your temple? The sun has to be coming in sort of from the side, I think, but I'm not sure on the exact angle.

But I don't think I've ever seen anything further away than my own face in the reflection in my glasses. More reliable is putting your watch right up to your eye and seeing behind you that way. It's not exactly inconspicuous, except, perhaps, when you have your head carefully positioned in your arms so that it looks like you're resting but you're really spying on the ceiling tiles.