Not clear on the subject

Overheard in the medic truck:

Medic 505: “So I see you’re allergic to Penncillin. What happens when you take it?”
Patient Experiencing Allergic Reaction: “I don’t take it, I’m allergic.”
M505: “But how do you know you’re allergic?”
PEAR: “My doctor said so.”
M505: “And how does he know?”
PEAR: “I had a reaction.”
M505: “Uh-huh. What kind of reaction?”
PEAR: “An allergic reaction.”

*facepalm*