Just went to my local cooperative store as I needed a lemon for a dish I was cooking. I take said lemon to the till with a few other items which the checkout assistant begins scanning.
She gets to the lemon and, I shit you not, says to me, "What is this?" I didn't know whether to 
or 
but I managed to utter, "Lemon, it's a lemon!"
As I also bought a bottle of wine on a school night! I know that she must have been at least 18!
So, MN, AIBU? Are lemons some exotic rarity that most people have not been exposed to?!