Whoa. I can think of two incidents where this could have been me: one where I could have been the subject, and one where I could have been telling the story.
First, when I was 18, I accidentally ate part of a peanut butter cookie at an event and didn't have my Epi-Pen with me. Fortunately we weren't very far from home (though knowing what I know now, 911 might have been a better option).
And then just last month, on vacation, the hotel restaurant messed up our order and gave our son a PBJ sandwich. Katie caught it before he ate any of it, and it's possible he hasn't inherited my allergy to peanuts, but we didn't want to find out that way.