The Coke Bottle Lens
I've heard it many times. "This camera lens is no better than a Coke bottle". If a Coke bottle is the reference for the worst optical performance you can get then I wonder exactly how bad it is.

I did of course not expect the statement to be based on empirical data. But to my surprise it is possible to get images from a Coke bottle! 

Looking at the bottle bottom from the side you can see that it is shaped like a positive meniscus. So there should be some optical power. The surfaces are however very irregular and bumpy.

I had to stop down the lens to about f11 to cut off most of the "bad" rays. So how bad is it? Judge for yourself. I must say though that I got much value for money. If you dare to drink the stuff you get the bottle for free. And you get an image...