I’m a registered nurse, not a doctor, but here’s the story:

Patient was a newly diagnosed diabetic who needed to be taught how to inject insulin. So the diabetes educator did the good old routine of taking an orange, drawing up insulin, then injecting it into the orange. He then made the patient repeat this practice routine a few times.

The patient goes home, etc. He comes back in a week and his blood sugar is out of control. They ask him if he's been taking his insulin and he goes "of course." So they decide to ask him to demonstrate how he injects insulin. The patient goes "sure, I just need an orange."

At this point I started face palming hard because I know where this one is heading. But of course they got him a orange and a vial of insulin with a syringe. So the guy draws up the insulin correctly, takes the syringe, injects it into the orange, and then says "and then I eat the orange."