It was the weekend and I was on a family outing. We drifted into a coffee shop and found a table without difficulty. My mother remarked that the table was dirty. I tilted my head by 30 degrees and sure enough I could detect some dark objects on the table. I do not know what they were and did not care to find out. Once the waiter had cleaned the table, I took another look. I got a nice clean sound with no obstructions. I am going to develop the habit of scanning every restaurant table.
It took some thinking to figure out what I was going to drink. I do not like coffee so settled for an Oreo shake. The shake came in a jar like container which was short but had a large diameter. I tilted my head down and saw this cylindrical structure. It was astonishingly dark. It appears that Oreo shakes are brown and do not allow light to pass through them. As I drank the shake, I kept glancing at the container and was able to detect an increase in light. Visual confirmation that I was getting through the shake.