I went to our local grocery store and could not find apple cider. I asked, "Where's the cider, sir?" He said, "I'm not sure. What does apple cider look like?" Once I eventually explained the physical characteristics of apple cider, the man said that they (this huge grocery store) did not have any apple cider.
I continued to look and found some by the deli.
Lesson learned: Don't assume everyone knows about apple cider.