Hearing someone has allergies to environmental things like dust or pollens hardly raises an eyebrow. Some food allergies are more common than others (e.g. shellfish, peanuts). But have you ever come across anyone having unusual allergies that you'd never heard of?
I went to highschool with a guy who was allergic to marijuana [Beavis](get it - HIGHschool huh huh[/Beavis] I also knew a kid in my neighborhood who was allergic to, well everything, but had an allergy to parrots. I have also heard of people having allergies to hops (and therefore could not drink beer ).