I went to the my local, neighborhood, grocery store tonight to pick up a few things for the week. As the high school kid - private high school - is checking me out he holds up a cabbage and looks at me and asks:

"Is this lettuce or cabbage?"
I tell him it's a cabbage.
"How can you tell the difference?"

I explain the difference.

Then he comes across a zucchini and asks if it's a cucumber. 

I was going to pay with cash, but decided against it.