I had a student in biology who very adamantly insisted she did not eat plants. We were discussing the celery we were using for a lab, she declared it to NOT be a plant because SHE did not eat dirty things from the ground.
I informed her that everything she ate either directly or indirectly, came from the ground. At this she yelled at me that her mother bought their food clean from the store.
By this time, the rest of the class was either laughing at her or just staring. I threw my hands up and said “well, I guess it just appeared out of nowhere at the store, POOF!”